Popular Science Monthly/Volume 52/January 1898/Carl Ludwig and Carl Thiersch

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1391628Popular Science Monthly Volume 52 January 1898 — Carl Ludwig and Carl Thiersch1898Wilhelm His Sr.



GENTLEMEN: Our medical faculty, as well as the whole University of Leipsic, were plunged in deep sorrow at the beginning of the term. In the course of a few days we lost Carl Ludwig and Carl Thiersch, two members of our academic association who for years past have been accounted among its ablest supporters. The death of these two eminent men brings to its close a period prosperous and brilliant for our faculty, during which a circle of talented and congenial companions worked harmoniously together. One after another during the past eleven years has left us—Radius, Cohnheim, Wagner, Coccius, and Braune—the younger men in some cases before the older; Carl Ludwig, Professor of Physiology, University of Leipsic. Born, December 29, 1816; died, April 23, 1895. and now two have followed whom we have always held in the highest honor, and without whom we could never have imagined our faculty as existing. An academic memorial service on such an occasion needs no further justification.

In the life of our universities, in spite of all seemingly uninterrupted activity and the continual substitution of failing powers by new and vigorous ones, a decided periodicity of development makes itself felt. In the whole university and in all the faculties, periods of rest and retrogression follow those of intellectual progress. External and internal conditions combine in producing this result, and it is not always easy to understand the influences at work. One fundamental condition, however, must necessarily be fulfilled in order that a corporate body may flourish: the body must have strong and clear-sighted leaders, who can direct its activity in definite channels, and insure a unity of purpose in all the departments.

Our faculty has had one of these leading spirits for several decades in the person of Ernst Heinrich Weber, who in 1821 became professor of anatomy, and later (in 1841) also took the position of professor of physiology. His Carl Thiersch, Professor of Surgery, University of Leipsic. Born, April 20, 1822; died, April 28, 1895. powerful personality has left its traces not only in the proceedings of our faculty, but still more noticeably in the sciences he represented and whose scope he extended in no small degree. Ernst Heinrich Weber, assisted by his brother Eduard, bore the double burden of the two important branches until 1865. In that year, however, it was decided to build a new physiological institute, and Weber, feeling that he no longer had sufficient strength to undertake the new duties that would now devolve upon the professor of physiology, decided to keep only his original position of professor of anatomy. Thus at Easter, in 1865, Wunderlich being at that time dean, Carl Ludwig was made professor of physiology and director of the new physiological institute.

In these changes the royal government took the initiative. At the request of their noble ruler, King Johann, the far-sighted leaders of the ministry, Secretary of State von Falkenstein and Geheimrath Dr. Hübel, had undertaken the task of raising the University of Leipsic to new importance and splendor with all the means at their disposal. The physiological laboratory was planned as the first of a series of new constructions, the final object of which was to be a complete revolution of the entire system of scientific instruction. In the choice of Professor Ludwig the royal government made a most fortunate selection, for it secured in him a man whose judgment and powers of organization made him a most able adviser in all its subsequent undertakings. In von Falkenstein's time, Ludwig's influence extended far beyond the sphere of the medical faculty, and some of the most important appointments of that time were due to his suggestion. Later, when at last instruction in the natural sciences had been organized in Leipsic, and the ministry of instruction had passed into other hands, Ludwig again confined himself to his own more limited department. His activity in this field, however, soon spread the fame of the Leipsic University throughout the world.

When Ludwig first came to Leipsic he was in the prime of mature manhood, and had already had twenty years of experience in teaching. He had begun his academic career in Marburg, in 1841, where he had been associated with his friend Ludwig Fick as demonstrator in anatomy. In 1849 he went from there to Zurich as professor of anatomy and physiology, and in 1855 he was called to Vienna to the medical military academy, the so-called Josephinum, as professor of physiology.

In 1852, during his stay in Zurich, Ludwig published the first volume of his text-book of Physiology, the second volume of which appeared four years later, when he was in Vienna. Ludwig's Physiology appeared like a meteor on the scientific horizon. It attacked the scientific knowledge of the day, demolishing former theories and conceptions with critical severity, and substituting new ideas and modes of expression which to us, the physicians of that time, seemed extraordinary enough. I well remember the sensations with which I, as an advanced student, on coming from one of Johann Müller's lectures, toiled through Ludwig's recently published work. Much that it contained I could only master by an effort, and much was actually repugnant to me, for it seemed to me to shatter to atoms the most interesting chapters of physiology as it had existed hitherto. And yet, in spite of all inward opposition, I could not resist the overwhelming influence of this powerful book with its vast stores of information, and I had to acknowledge more and more the force of its triumphant method of presentation.

Wherein lay the great step in advance that Ludwig had taken with his Physiology? Ludwig was a pronounced physical physiologist. A physical physiology had, however, existed long before his time. During the preceding two centuries there had already been schools of mechanical therapeutics in which classical works, as those of Borelli on animal movement, of Hales on blood-pressure, had been produced. Beginning in the second decade of this century, the Weber brothers had proved themselves investigators of the first rank, and their fundamental experiments on wave motion, the pulse, human locomotion, on muscular contraction, etc., were founded on a strictly physical basis. Other men of similar ideas, among them A. Volkmann, subsequently joined them. From the time of Lavoisier, works had been coming from France in which physiological questions were treated in a thoroughly physical method—the treatises of Dulong and Despretz on heat production and dissipation, those of Poiseuille on the circulation of the blood, and, lastly, the exhaustive work on respiration by Kegnauld and Reiset. Among Ludwig's personal friends, E. Du Bois-Reymond had between 1840 and 1850 constructed a theory of molecular physics of the nerve and muscle tissue, and Helmholtz, by means of wonderfully ingenious methods, had measured the rate of transmission of the stimulus in living nerves.

The road for physical investigations in physiology was, therefore, already open when Ludwig's book appeared. Moreover, the idea of a vital force, which on account of its obscurity had excited so much opposition, had now become meaningless for scientific investigation, and had besides received its deathblow through Lotze in 1842. What, however, was totally lacking before the appearance of Ludwig's book was a thorough introduction of physical reasoning and methods in physiological instruction. Anatomy was still the ruling branch of science even in physiology, and in some chapters of the latter the physiological problems were actually left out m favor of anatomical or comparative anatomical explanations. This was the more natural, because physiology was still taught by anatomists in most of the universities. Moreover, the regular course of instruction afforded the young physician abundant opportunity of acquiring a thorough anatomical education, while on the other hand a more rigorous training in physics was extremely difficult to obtain. Even to the present day this difficulty has never been satisfactorily overcome.

As anatomical demonstrator and professor, Ludwig himself had been through the dissecting room; he was all his life an excellent anatomist, and thought exceptionally highly of the mission of anatomy. However, in many ways his ideas of this mission differed from those of his predecessors, and even his language was often unlike what had hitherto been in use. He was especially energetic in opposing the idea that the mere description of forms could lead the way to a true understanding of physiology. The controversies between Ludwig and his opponents were vigorously carried on for several years, but at last they grew to understand one another better, and anatomists now have for years been accustomed to respect Ludwig as a valuable fellow-worker and one of the most eminent promoters of their science.

Perhaps nothing is more significant of Ludwig's point of view at the time of his first appearance than the arrangement of matter in his work on physiology. Ludwig's great predecessor, Johann Müller, had prefaced his manual of Physiology with a general chapter on organic matter, on organisms and life, and then proceeded to a description of the great vital functions: the formation and circulation of the blood, respiration, nutrition, etc. Ludwig, on the other hand, began his presentation with a Physiology of Atoms and of Conditions of Aggregation. As an ideal form of investigation, he conceived the possibility of deducing the functions of complicated molecules from the conditions of their elementary construction, thence, however, to continue step by step to the tissues, and subsequently to the organs. Thus he thought to construct an intelligible theory proceeding from the simple to the complex, and at the same time to determine with mathematical accuracy the derivation of the one from the other in respect to direction, time, and quantity, and to prove the existence of each as the necessary outcome of a natural law.

The theoretical need of an elementary foundation for physiology caused Ludwig in his earlier years to study certain fundamental physical processes, such as filtration, diffusion, and the laws of hydraulics, with especial attention, and to make use of the knowledge thus obtained to explain the phenomena of animal life. Later he grew far more cautious as regards these explanatory experiments, and references to the organic connections of vital processes are much more frequent in his later work. He now speaks with especial predilection of the wonderful mechanism of life, the intricate workings of which, in all its complications, it is the duty of science to reveal.

I here quote a few words from the speech that Ludwig delivered on entering on his professorship at this university: "Physiology," he said, "has entered with full consciousness the sphere of mechanics, where rigorous laws obtain, and where the inexorable logic of circumstances rules the course of the atoms; but we, the heavily burdened servants of science, have armed ourselves with a thousand weapons with which to pursue the intangible phenomena of Nature, and, reflecting on these, we endeavor to understand the subtle mechanism of life. And when we finally receive our reward, when we at last comprehend an organ in all its connections, our proud consciousness is crushed by the knowledge that the human discoverer is but a bungler beside the unknown creator of animal life. For when man compares himself with him in the solution of any problem, he must ever fall short, as does the telescope compared with the eye, and the litmus paper with the tongue. And if all this was once clear, why must it needs again become obscure to us?"

If, however, we desire to understand Ludwig's full importance, we must seek him in his laboratory, and in the midst of his pupils, for here his most characteristic and noblest qualities reached their fullest development. A summary of Ludwig's and his students' work can only be indicated here. With his endeavor to make the construction of the body physiologically comprehensible, Ludwig, unlike some of his friends who were engaged in the same line of work, did not confine himself merely to physical experiments, but devoted most of his activity to the far more difficult task of experimenting on the living body, a branch of work which in his hands and by his own inventions, the "Kymographion," the "Stromuhr," the mercury pump, etc., gained a precision that up to that time had never been imagined.

His inaugural thesis, that appeared in 1842, at first opposed by the Marburg faculty, treated of the secretion of the kidneys, a subject to the study of which he returned again and again in later years. Another very systematically arranged line of experiments led Ludwig in 1851 to the important discovery of the dependence of the secretion of the saliva upon the irritation of the glandular nerves, and to the recognition of the independence of the pressure of the secretion from that of the blood. This discovery was of fundamental importance for the physiology of secretion no less than for that of the nervous system, and it was at that time all the more surprising, since Ludwig's own suppositions had caused precisely the opposite result to be expected.

Constant objects of intense interest to Ludwig were the peculiarities of the circulating blood, its lateral pressure, and its rate of flow, as well as the dependence of these functions on the activity of the heart, on that of the muscles of the body, on the condition of the vascular muscles, and of numberless other factors. It is in this field that Ludwig's delicate graphic apparatus and his precise methods of measurement won their greatest triumphs. No less are our thanks due to him for a great part of the present knowledge of the mechanism of the heart's activity. It was he who first gave us an idea of the action of the lymph current in the living organism. He determined quantitatively its amount and its variations, and by histological investigations on the origin of the lymphatic system he threw light on the nature of this extraordinary apparatus. Ludwig labored incessantly to obtain a true understanding of respiration, including not only the gas exchange in the lungs, and the respiratory movements, but also the internal or tissue respirations. He was very successful in studying the activity of organs in the so-called state of survival which is produced by conducting a stream of blood through parts taken from a freshly killed animal, and thus the qualities of the blood, the lymph, as well as of various secretions, are determined and compared, both before and after the passage of the blood. When it seemed to him necessary to extend the anatomical foundations of physiological study, he always undertook this himself, or required students to make anatomical investigations. Among many other histological researches, we are indebted to him, above all, for his classic treatise on the structure of the kidneys. The most careful investigations of the blood-vessels of the eye and those of the inner ear were also made in Ludwig's laboratory. In fact, by the establishment of the histological department of his institute, he exercised a marked influence on the development of minute anatomy.

If Ludwig's experimental methods were characterized from the beginning by their extraordinary precision, this quality was simply the result of the serious cast of his whole character. At whatever time one might happen to enter his laboratory, one always received the impression that it had just been put in order, and that every article was in its proper place.

The numerous investigations which Ludwig caused to be made on the most important parts of the body of course furthered the advance of medical science. The results of his researches benefited theoretical medicine, and his fully developed methods were of great advantage in experimental pathology and in clinical observations. Among Ludwig's pupils were a large number of eminent clinicians. Ludwig himself, however, always attached great importance to his relations to medicine and the practical significance of physiology. "Guiding the course of human life according to the dictates of human wisdom" is what in his great work on physiology he gives as his conception of the true aim of a physician, and later he several times expressed the same idea in somewhat different words.

It would be extremely interesting to follow more closely the influences that caused Ludwig to take up the physical side of physiology. This is now no easy matter to determine, and even inquiries that I have made among his surviving friends and pupils have given me no definite opinion. An accurate manner of thinking and great mental independence were always peculiar to Ludwig, and they were perhaps the qualities that caused him to turn aside from all beaten paths. As a student, this feeling of independence brought him into conflict with the laws of discipline in his university, and resulted in a temporary suspension of his studies there. On his return to Marburg he seems to have finally decided on making physiology his profession, and it was then that he entered Bunsen's laboratory. In the analyses that were undertaken there he probably had his first opportunity of becoming familiar with the more accurate physical methods. There he also had intercourse with other young physicists, among whom was Reiset. Bunsen's strict training must, indeed, have been a strong contrast to the unsystematic routine of the Bamberg surgeon with whom Ludwig had spent his time of suspension. From 1842 (the year of the inaugural thesis) onward he worked on the problems of physical physiology with his friends and pupils.[2] When, in the course of a few years, the new school of physics in Berlin was formed, he entered on a correspondence with its representatives—with E. Brücke, E. Du Bois-Reymond, and H. Helmholtz. Ludwig's first opportunity of meeting these somewhat younger friends was in 1847, when he made a short visit to Berlin. It was then that he also made the acquaintance of E. H. Weber and A. Volkmann. He seems to have led Volkmann to the use of his recently invented kymographion, for, as is known by common report, they experimented together for a time.

In his manner of investigating, Ludwig was all his life a most acute analyzer, seeking with the utmost care to separate every vital process into its various branches, and to determine the conditions of its manifestations. In this work he always attached great importance to the quantitative determination of all the factors of the problem. This manner of work of course often resulted in the questions that he had investigated seeming further from a satisfactory solution than before he had begun; Ludwig, however, never regarded any line of research as definitely closed, but years later returned again and again to work on the problems he had undertaken to solve, and continued his researches with the help of his added knowledge and experience. Herein lay one of the most interesting sides of his richly endowed nature; in his search for the truth he never faltered, but with untiring energy continually attacked the problem with new weapons.

Ludwig's mode of scientific work was entirely opposite to E. H. Weber's. Weber possessed the gift of artistic intuition. He absorbed himself in his problems until he believed that he had mastered the main substance of the matter, after which he was able in a few clear strokes to draw an illustration of oftentimes wonderful simplicity. Weber's scheme of the circulation, constructed by the insignificant means of a piece of intestine and a few lamp chimneys, solved with one stroke, convincing even to beginners, some of the most abstruse problems of the theory of the circulation, and even the complicated technique of later physiology has not been able to dispense with it. The first one to recognize this was Ludwig himself; in fact, he went so far as to consider Weber's discoveries of greater importance even than Harvey's discovery of the circulation of the blood. Intuitive natures, such as Weber's, may make particularly clear teachers. The artistic perception, however, which is their most valuable quality, can not be transferred to others, and thus we seldom find them as founders of any school of science. Thus Weber, if we do not include his personally congenial friends, never in all his long career attracted scientific pupils. Ludwig, on the other hand, made

a success in this direction with which in this country we can only compare Liebig's successful instruction in Giessen.

The power of attracting young men and interesting them in scientific questions was early noticeable in Ludwig. At Marburg, already in the year 1842, we find him working in connection with his scholars, or, as he always designated them, "his young friends," among whom some, such as C. Eckhard and Ad. Fick, afterward became his physiological colleagues. In the same way, during his six years' stay at Zurich, he gathered about him as fellow-workers in his researches all the stronger elements there. His power of attraction soon spread beyond the limits of the university, and later in Vienna, and finally here in Leipsic increased in a nearly geometrical rate of progression. The number of young men from all over the world whom Ludwig has guided to independent investigation has increased in the course of years to several hundred, and we see on the list some of the first names of our modern scientific world. Yet all Ludwig's pupils have all their lives looked up to him with deepest gratitude and affection, and have recognized how much they profited just from him in the line of intellectual education. "I owe Ludwig," a prominent investigator wrote me recently, "my scientific conscience, and instinctive repugnance to any bungling."

In trying to account for Ludwig's wonderful gift for teaching, I find the first main condition in his highly ideal spirit; the second, however, in his deep love on the one hand for investigating and on the other for aspiring youth. Only he who feels deeply can attach others to himself for any length of time. When Ludwig spoke of his pupils as his young friends this was no mere figure of speech; he was in reality personally interested in them, and even after many years had passed, still followed their later career with all the sympathy of a true friend. When he gave the young men who came to him scientific work to do, and with unselfish devotion taught them the first principles of physiological thought, interrogation, and method, his power of combining the qualities of teacher and fellow-worker was unsurpassed. He knew, moreover, how to deal with each one according to his particular nature, and the large field of work he controlled made it possible for him to give suitable work to pupils of the most varied talents and training. One he placed in the chemical laboratory, another before the microscope; to sensitively organized natures he gave delicate experiments to do, and even if a clumsy worker applied to Ludwig, he was not disappointed, but was placed in the care of that careful and experienced assistant, Salvenmoser. Even if such a pupil was never able to do independent work, he at least had the opportunity of learning by his own observation the great importance of order and precision in all scientific undertakings.

Ludwig's disinterestedness toward his pupils went to such an extreme that he allowed works that had been accomplished under his immediate supervision—generally, in fact, executed by his own hand, and also, as a rule, prepared for editing by him—to go out into the world under the name of the pupil who had assisted him. He not only did this in the latter years of his life, as a world-renowned scientist, but as early as the time of his stay in Marburg, at an age and in a position in which young men are usually less generous with their names. Under the names of Mogk, Spengler, Becher, and others, Ludwig's youthful investigations went forth, and when in 1847 he published his invention, the kymographion, under his own name, he apologized for it, saying that his young friend Gerau, then otherwise engaged, should really have done this. And yet in this case it was the question of one of the most important discoveries in natural history, in view of its later consequences. Ludwig, by means of his kymographion, introduced the principle of self -registering apparatus into science—a principle the importance of which may well be compared with that of the microscope, for it was first by means of such apparatus working as time microscopes that it became possible to directly observe and comprehend rapid and complicated processes.

As with the pupils in his laboratory, Ludwig also associated with his students with friendly sympathy. They all felt this, and returned it with warm attachment and respect. They usually attended each of his lectures two or three times, as the beginners were hardly able to master the information they received at the first hearing. In especial physiological conferences Ludwig gave the students opportunity of talking with him personally. For my part, it was a continual source of astonishment to me to see how accurately Ludwig was informed with regard to the industry and talents of the individual students.

Ludwig's workroom was a place to which the most heterogeneous elements had free access—foreign scientists, colleagues of all the faculties, physicians, friends, and pupils. There one might at any time seek his advice and enjoy the magic of his society. With his many-sided and thorough education, and his ever quickly roused enthusiasm for all sorts of new problems and lines of work, it was easy to interest him in questions of the most varied character. His great knowledge of the world and of human nature made his conversation a never-ending source of interest and information. Ludwig's point of view was ever lofty; the lines of thought on which he worked were always original, never commonplace. With his subtle humor he would occasionally maintain a paradoxical opinion. If, however, he was opposed by arguments that were repugnant to his idealism, he was also capable of uttering bitter and sarcastic words. His conversation always inspired active thought.

Yet, with all the pleasantness of this social intercourse, his strict self-restraint, the strongest quality of his nature, was always manifest, and this was one of the principal causes of the excellent influence he exercised over young people; they had in him the example of a man who was scrupulously strict with himself, and absolutely conscientious. "Ludwig was also our professor of ethics," one of his American pupils recently remarked to me. And thus Ludwig's life has amply proved that the best and highest that a teacher can give to youth lies in the power of his own personality.

Ludwig's coming and the erection of the Physiological Institute caused a revival of theoretical instruction in our faculty. Two years later the arrival of Thiersch was followed by great changes in clinical instruction. Clinics have only existed in Leipsic since 1798. Up to that time the faculty had professors of pathology and surgery; learned men, who, however, gave no hospital instruction. Even when by the courtesy of the magistrate, and especially through the efforts of the excellent burgomaster Mūller, the City Hospital had been opened for clinical instruction, the clinical teachers for a long time had only a subordinate position in the faculty. Only later, in 1812, the professor of clinical medicine (A. Clarus), and in 1824 the demonstrator of surgery (Kuhl) were received into the faculty as full professors.

A report of the faculty of the year 1838, written in Weber's clear handwriting, gives the key to a true understanding of these curious conditions. The Jacob's Hospital, in which the clinic was held, was then, as now, a city institution, the doctor and surgeon of which were appointed by the magistrate, and only later on were confirmed by the government. The first was appointed clinical professor, the latter surgical demonstrator. The financial support from the government was limited to four hundred thalers as a salary for the clinical professor, and one hundred thalers as a salary for the demonstrator of surgery.

The expenses of the hospital fell entirely on the city, the natural result being that the admission of patients was carried on without any reference to instruction.

The above-mentioned report complains bitterly of the existing conditions, and dwells on the fact that the sick-beds were almost entirely taken up by cases of chronic disease, which were practically useless for purposes of instruction. How curious it is now to hear that in 1838 the want of surgical cases was explained by the smallness of Leipsic and the "comparative wealth of the laboring classes"! The surgical demonstrator was subordinate to the clinical professor, and his duties consisted merely in admitting students twice a week to his visits among the sick, and in winter demonstrating the most important operations on the cadaver. The faculty now in an entirely professional manner desired the government to provide clinical free beds, twenty medical and twenty surgical. To this request was added a list of suggestions for the organization of a course of instruction in clinical surgery, for the furnishing of a collection of instruments, and for a practical operative course.

The adoption of these recommendations of the faculty was the first decisive step toward a more perfect organization of surgical instruction; a second step was taken in 1841 through the appointment of Professor Günther, of Kiel, as professor of surgery and surgical demonstrator. Thus the existence of a regular surgical clinic in Leipsic dates back hardly fifty years. Even then the conditions of its existence were unfavorable enough, and hospital gangrene, in spite of the open-air barracks devised by Günther in the surgical department of the hospital, was a matter of inevitable recurrence. The surgical clinic only attained its full development a generation later, under Thiersch. It was also he who put an end to the unworthy subordination of the surgeons to the physicians.

Günther died in 1866, and after his death it is again a report from the pen of E. H. Weber which sets forth the point of view of the faculty. The first necessity seems to be now to provide a more suitably arranged hospital; the faculty therefore insists on the importance of appointing a man able to undertake the task of organizing its erection. This requirement was entirely fulfilled by the appointment of Thiersch in the following year, 1867.

At the time when the task of attending to the building of the new Jacob's Hospital with Wunderlich fell to Thiersch, the allied questions of surgical treatment and of hospital construction were undergoing a thorough revolution. As early as between 1850 and 1860 French physicians had recognized the mortifying fact that in English hospitals the number of successful operations was incalculably larger than in their own. The most careful examination of the conditions of both resulted only in the discovery of the far greater cleanliness and better ventilation of English institutions. Moreover, an English physician, Spencer Wells, had applied the principle of absolute cleanliness to operations in the abdominal cavity with startling success, thus making these previously almost necessarily fatal operations comparatively harmless. During the American civil war, important knowledge as to the best conditions for the treatment of wounds was gained. It was discovered that the wounded recovered most safely and rapidly in the airiest apartments, in lightly built barracks, or in open tents. Thiersch, with his keen insight, at once recognized the advantages of the American system, and he was the first in Europe to have a large hospital built on the plan of barracks. In the Jacob's Hospital, which was built according to his directions, there are a great number of long-shaped buildings in a park, so distributed that the two long sides of each are free, and having at one end an airy veranda, into which beds may be pushed at any time. Air and light, these two "unpaid but invaluable assistant physicians," as Thiersch said, have free access to every patient. The system proved so excellent that in the course of years more and more barracks have been added, and the Jacob's Hospital has long been regarded far and wide as a model of such an institution. When, soon after the opening of the hospital in 1871, Lister's beneficent methods of surgical treatment were made public, it was again Thiersch who at once recognized their enormous significance, and advocated them with all his power. This beautiful hospital offered him the best possible conditions for the carrying out and further development of the newly acquired methods, as well as for their introduction in the education of the younger medical generation. There he worked during the past twenty-four years, not only as a teacher revered by all, but also as a faithful physician; and he so loved his hospital that even during his time of suffering he occupied himself ceaselessly with it, and one of the last wishes he expressed was that he might be able to return there once more.

Carl Thiersch, when he came to Leipsic, had occupied the chair of surgery in Erlangen since 1854, before which he had for six years been prosector in the Pathological-Anatomical Institute in Munich. He seems to have acquired his tendency toward surgery in 1850, during the second Schleswig-Holstein War, in which he served as volunteer physician under Stromeyer.

It is much more difficult to appreciate Thiersch's works in their connection than Ludwig's. In the case of the latter, when as a young man he came before the public, we have to do with an intellectual force of great intensity, and of a scientifically well-defined tendency. His whole life was given to the accomplishment of certain objects which he had placed before himself in the beginning of his career, and in following the coarse that was to lead him to his aim, he persistently sought, in all his work, to attract intelligent young men to his scientific researches.

Thiersch's development was of a different nature, and in order to understand what he accomplished it is necessary first of all to study his personality. Descended from a well-known scientific family, Thiersch brought with him the taste for thorough knowledge and for delicate intellectual understanding. He possessed the strict desire for truth and the independent disposition of the true scientist. He loved, moreover, to absorb himself in especial problems, even when they really did not belong to his department. His address as rector at Erlangen on teaching and studying, and especially his Hamlet Glossary, show how much he also liked to devote himself to problems of human psychology. With all this tendency toward the subtleties of mental analysis, Thiersch was yet an accurate observer, and full of sound common sense. Endowed with such qualities, he easily developed into a clever and experienced judge of human nature. His fine command of language made him a spirited and much-admired speaker. As a general thing, however, he made sparing and thus most effective use of this gift, and even in expressing serious thoughts he often employed the weapon of a never-failing humor.

Thus Thiersch was one of those harmoniously gifted and well-rounded natures who have the power of accomplishing well any task that presents itself to them. As scholar, investigator, and physician, in the service of peace or of war, as well as now and then in executive positions, he always filled his place and accomplished excellent work. He never put himself forward, but rather let people and things come to him; yet nothing was further removed from him than ostentation, whether as regards his erudition or any other of his mental endowments. He preferred to hide his fine qualities beneath a mantle of dry humor. Those who did not see this absolutely conscientious man at work might well be doubtful as to his real earnestness. He was, however, extremely sensitive to vanity and obtrusiveness in others. When he met with these qualities, he could repel their owners severely by dignified reserve or by pointed remarks. The students who were aware of this danger perhaps avoided it with unnecessary care.

Thiersch's scientific works, whether on theoretic or practical questions, produce an impression of great maturity and perfection. Often original in their conception, they are always very careful in their plan and execution, and clear in the form of their presentation. His first printed essay, a medical dissertation on materia medica, still shows Schelling's youthful pupil. In the language of natural philosophy, he tries in it to deduce the action of medicaments from principles of the most abstract kind. But Thiersch did not remain long in this field. In his next works, which he undertakes as prosector, he proves himself already a creditable and thoughtful naturalist. It is the same in his investigations on pyæmia, on the formation of the sexual organs, and in his great experimental treatise on the origin of cholera. When Thiersch became a surgeon, his thorough theoretic knowledge was again and again of use to him, and he also was able to employ to great advantage his remarkable skill in injecting fine blood-vessels. His most celebrated work is the monograph on epithelial cancer, in which he first determined with precision the origin of malignant tumors, and at the same time drew the most important practical conclusions from an essentially embryological idea. His excellent treatises on the healing of wounds and on transplantation of the skin are no less based on theoretical preliminary study. The certainty of his surgical methods was with Thiersch the result of his anatomical and pathological knowledge. In a thoughtful obituary notice, Professor Landerer, one of his former pupils, writes: "Thiersch's operating was the direct outcome of applied and pathological anatomy. With his phenomenal knowledge of these departments he could allow himself to build up his plan of operation directly on the diagnosis, and always to proceed as a free, creative worker."

Thiersch is reported to have said of himself that he was really an anatomist gone astray. In the interest of suffering humanity, however, it was surely well that he turned from anatomy to surgery, for he was a surgeon by the grace of God. He possessed not only the necessary firmness of eye and hand, but also a sovereign calmness that even in the most trying situations never failed him. Above all, the most beautiful quality that a great physician can have was his: he was possesssed of delicate sensibilities, and was thoroughly humane in his disposition. This last quality was perhaps the most prominent of Thiersch's many virtues, yet it was the one he endeavored most carefully to conceal. He burdened his heart with every one of his seriously sick patients; in critical cases he hurried to the hospital at the most unusual times, and if, contrary to his expectations, a serious operation resulted unsuccessfully, it was often days, and even weeks, as Landerer tells us, before he could reconcile himself to the result. He would criticise himself severely in order to determine whether he had not some mistake or neglect with which to reproach himself.

Thiersch's favorite resort was the children's wards. There he could devote himself to each without reserve. He remembered each of his little patients, and when, after their leaving the hospital, he occasionally met them in the street, he used to speak with them and inquire after their health. And for this the "Herr Geheimrath" was deeply revered by all who had been his patients, and it was a festival for them when his birthday or some other occasion gave them an opportunity of showing their affection by some little attention.

I should overstep the limits of an academic discourse if I followed further the tender side of Thiersch's personality. Yet one thing I must not pass over: that is, the beneficent influence of his humanity upon his pupils. It is only too easy for young physicians to become callous to human suffering, which they are daily called upon to witness, and unless carefully guided by a teacher their manner toward patients may easily become inconsiderate. Like his deceased colleague, Wagner, Thiersch was one of those teachers whose benevolent dispositions exercised an ennobling influence over their pupils, and at once checked any tendency toward coarseness in word or thought.

The striking power of Thiersch's personality was at once felt by any one with whom he came in contact. His decisive bearing, his clear and sure judgment gained great respect for him in all circles. Among his surgical colleagues and at our academic meetings his opinion was depended on as a decisive one in all difficult questions.

As companions in the faculty, Ludwig and Thiersch supplemented one another admirably. Each one fully appreciated the other's value. Ludwig's aims were always of an ideal nature and always high. In the struggle to reach them he knew no compromise. It often seemed to me as if Ludwig, in his somewhat austere severity, was the embodied conscience of the faculty. Thiersch, on the other hand, with his intelligent insight, always knew where to find the starting point from which the object to be sought for was accessible. Both men were equal, however, in their sincerity and in the independence of their dispositions, both absolutely free from private considerations, and only anxious for the well-being of the institutions intrusted to them.

The names of Carl Ludwig and Carl Thiersch will be reverenced by our university for many years to come. Long will she be proud to have possessed two such large-minded and noble men. Such a possession is lasting in its consequences, for it will have an elevating and strengthening influence on coming generations. The memory of both men will always be blessed.

While fully recognizing the influence of the inheritance of the imagination of his grandfather and the acute observation of his father on the formation of Darwin's scientific habits, Mr. A. R. Wallace mentions as other factors which have been usually overlooked the five years' voyage and his persistent ill health. During a very large portion of the five years on the Beagle, Darwin must have been practically alone and thrown on his own mental resources; and this mental solitude of an active mind, furnished continually with new and interesting facts on which to exercise the imaginative and reasoning powers, led to the formation of those original and suggestive ideas which were the foundation of his greatness. Hardly less important was the almost continuous ill health, which, while not preventing work or shortening life, obliged him to live in the country, free from the distractions of society, where his active mind could only be satisfied by continual study and experiment.
  1. Memorial Address. Translated by Ethel Bowditch.
  2. Among the standard works which he recommended to them at that time were the writings of the Weber brothers (Die Wellenlehre, 1825; the treatises on the pulse, absorption, auditory and cutaneous sensation, 1834; and the locomotive organs, 1834), Poiseuille's works on the circulation of the blood (1832), and Johann Müller's investigations on the formation of the voice.