Popular Science Monthly/Volume 50/January 1897/Botanic Gardens II

by Daniel Trembly MacDougal

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BOTANIC GARDENS.

By D. T. MACDOUGAL,

ASSISTANT PROFESSOR OF BOTANY IN THE STATE UNIVERSITY OF MINNESOTA.

II.—TÜBINGEN AND ITS BOTANISTS.

THE botanic garden connected with the old Würtemberg University at Tübingen is worthy of special notice, because of its history and its importance as a center of research in the biology of plants at the present time.

The university with which it is connected was endowed more than four hundred years ago by the reigning house of Würtemberg, and during the entire period of its existence it has enjoyed the exclusive patronage of the grand ducal and later the royal family, as it is the only higher institution of learning within the kingdom. Set as it is among a hardy and virile people, it has been the scene of many notable mental victories over tradition and superstition. It has always held a position in the forefront of human advancement, and its splendid achievements mark epochs in human thought. Here have originated great schools or methods of thought in the different branches of human knowledge. Bauer in philosophy and von Mohl in botany have each forwarded research in his respective line in a manner that can not be measured or easily estimated.

The subject of botany in this institution received its first attention from the side of medical science. With the introduction of the laboratory method of instruction, actual demonstrations of plants were used to supplement the lectures. To meet the need of material of living plants the garden was founded in due time, and it has at successive periods represented quite accurately the development and extension of botanical science,—a development to which the botanists of Tübingen have largely contributed. The subject of botany here has always been in the hands of workers of the first rank, who each in turn have materially advanced the frontiers of knowledge of the biology of plant life, for a period extending over three and a half centuries.

The first lectures on plants, dealing with their medical properties, were given at the university by Leonard Fuchs, from 1535 until his death in 1566, although it was not until a century later (1662) that the garden was founded. Fuchs occupied a prominent position in the history of ancient botany, since he made the first attempt to establish a system of terminology, and furthermore he was the first to base descriptions of species upon facts obtained from an actual examination of the plants themselves. In his Historia Stirpium about five hundred species are figured and described, and the woodcuts in this quaint old herbal are of value even at this time. It is to be borne in mind, however, that Fuchs had formed no idea of the natural relationships of plants. The species given in the herbal are arranged in alphabetical order. It seems almost inconceivable at the present day, yet the descriptions of plants made by botanists in the period preceding Braunfels (1530) and Fuchs were not taken from nature, but were borrowed from still earlier writers, and supplemented by additions drawn purely from fancy and colored by the superstition of the time.

The establishment of the garden in 1663 was purely for the purpose of conserving medicinal plants, and only such species

Simon Schwendener, Professor of Botany and Director of the Botanic Garden, 1878. After a photograph by T. Barzuck, Berlin.

were cultivated as could be grown in the open air. The art of growing plants in artificially heated glass houses was not understood at that time. The garden occupied a plot of ground lying on the banks of the Neckar in what is now the heart of the city of Tübingen, where it remained until 1805, when it was removed to its present position. The lectures in botany in the university took on a new dignity when a separate chair was devoted to the subject by the appointment of Rudolph Jacob Camerarius as extraordinary professor and director of the botanic garden in 1688. He was afterward promoted and remained at the university until his death, in 1728. Camerarius made a most notable addition to botanical science by the actual experimental demonstration of the principal facts in the pollination of plants (1691 to 1694). Sachs says in his history of botany: "Camerarius had observed that a female mulberry tree once bore fruit, though no male tree (amentaceis floribus) was in the neighborhood, but that the berries contained only abortive and empty seeds, which he compared to the addled eggs of a bird. His attention was aroused, and he made his first experiment on another diœcious plant (Mercurialis annua). He took, in the end of May, two female specimens of the wild plant (they were usually called male, but he knew them to be female) and set them in pots apart from others. The plants throve, and the fruit was abundant and filled out, but when half ripe they began to dry up, and not one

Wilhelm Pfeffer, Professor of Botany and Director of the Botanic Institute, 1878-1887. After a photograph by W. Hornung, Tübingen.

produced perfect seeds. His communication on this subject is dated December 28, 1691." The importance of his discovery was not recognized at the time, and his conclusions were accepted in a figurative sense only. Not until the end of the following century was his experimental evidence used as a basis for further researches by Kölreuter. Linnæus, to whom great credit is given by many writers for his share in the development of the theory of the sexuality of plants, ignored the facts disclosed by Camerarius, and arrived at identical conclusions in a purely deductive manner, arguing from the necessities of the case.

After the demise of Camerarius he was succeeded by his son Alexander. Later the lectures on the subjects of botany and chemistry were given by one professor. After a short interregnum the subject was once more in the hands of a master spirit in the person of Joseph Gaertner, who was called to the chair of botany in 1760. Gaertner remained at Tübingen eight years, going to St. Petersburg to accept the chair of botany in 1768. He returned to Calwe in 1770, and published shortly afterward his De Fructibus et Seminibus Plantarum, which may be truly termed an epoch-making work. The study of fruits and seeds had languished for more than a century, and Gaertner came to it with a mind singularly free from prejudice. He was aware of the real value of fruits for the arrangement of plants in a natural system, but he did not attempt to found a system on such material alone. Having at hand a most extensive collection of plants from around the world, which he studied with a persistence that brought him nearly to blindness, his book is an inexhaustible mine of facts and a guide to the morphology of fruits and seeds. His collection of material and microscope are still preserved in the botanical museum.

The lectures in botany at the university were placed in the hands of Friedrich von Kielmeyer as professor of natural philosophy in 1805. At this time the garden was removed to its present location, on the banks of the Ammer, in the northwestern part of the city, and shortly cold and warm houses for plants and a residence for the university gardener were erected. Kielmeyer was succeeded by Schubler in 1817, and he in turn by Hugo von Mohl in 1835.

It would be difficult to overestimate the value of the work accomplished by von Mohl during the thirty-seven years (1835 to 1872) in which he was professor of botany at Tübingen. This period does not include the entire time of his activity in this place, however. In 1826 the faculty of medicine offered a prize for an essay on the nature of tendrils and climbing plants, and a thesis by von Mohl, who was then a student, won the prize. This academic essay, written at the age of twenty-two, remained the clearest presentation of the subject until it was taken up by the elder Darwin in 1865. During the half century in which he was

 

Hermann Vöchting (sitting, facing front) and Group of Workers in Botanic Institute in Summer of 1896; Professor of Botany and Director of the Botanic Garden since 1887. After a photograph.

 

a leading figure in the botanical world, he used a purely inductive method of research, and by a long series of many-times repeated observations established manifold phenomena and facts which he welded into a coherent mass by a logic so relentless that he was incapable of being led astray into fanciful theories and dazzling speculations. Such a method enabled him to take a prominent part in the destruction of the chimerical teaching of the nature philosophy, especially in regard to the doctrine of the metamorphosis of plants. Furthermore, he succeeded in establishing the principles of anatomy so clearly that a rational system of morphology became possible for the first time. So important and basal were his demonstrations concerning the real nature of the primordial utricle that by many botanists he is said to havediscovered protoplasm (1846). Von Mohl, with Schlechtendal, established the Botanisclie Zeitung in 1842. The list of his works includes ninety titles, embracing subjects in every department of the science. During his administration at Tübingen the garden was enlarged by three additions, to its present dimensions, occupying an irregular tract of land on both banks of the Ammer; important additions were made to the glass houses in the garden, and the institute building was erected in 1846. Perhaps no greater tribute can be paid to von Mohl's broad conception of the scope and needs of botany than the fact that this institute building erected fifty years ago, remains practically unaltered to the present day, and is still found fairly available for the purposes of modern investigation.

Upon the death of von Mohl, in 1872, he was succeeded by Hofmeister, who died after having held the post but five years. Hofmeister had perhaps accomplished his more important results before his stay at Tübingen. Like von Mohl, he used an inductive method of investigation, and he as well made enormous contributions to the material facts upon which many of our present generalizations in morphology rest. The results of the investigations published in his Vergleichende Untersuchungen in 1849 remain to-day superior to anything achieved in descriptive botany. To Hofmeister must be ascribed, among other important embryological results, the discovery of the alternation of generations in plants, and by the use of his phylogenetic mode of study the ideas concerning natural affinities of the groups of cryptogams and phanerogams underwent an almost total alteration. His establishment of the genetic relationship of these great subdivisions resulted in the overthrow of the prevailing belief in the constancy of species.

Prof. Simon Schwendener succeeded Hofmeister as director of the institute and garden in 1877. He, as well as his two successors, are still in the midst of active work, and it is by no means easy to forecast the final value of the results of their investigations upon the development of the subject. Schwendener has made very important contributions to the biology of lichens, phyllotaxis, besides a long series of contributions of the first rank in the domain of morphology and physiology. Among these his Mechanische Princip in der Bau der Monocotylen is of the greatest importance. Schwendener remained but a year at Tübingen, going thence to the University of Berlin, where he vigorously continues his researches. In consequence of his short stay but little of his work was accomplished at Tübingen.

The direction of the institute and garden was assumed by Prof. Wilhelm Pfeffer in 1878, who remained in the place nine years. The splendid results accomplished by himself and students during that time are published in a set of two volumes entitled Untersuchungen aus den botanische Institut zu Tübingen. The work dealt with the principal problems of physiology in growth, turgescence, secretion, movements, respiration, and nutrition. In 1887 Pfeffer removed to Leipsic. Both before and after his stay

 

View of Palm Houses, Work Rooms, and Herbarium, in Autumn. After a photolithograph in "Die unter der Regierung seiner Majestät des Königs Karl an der Universität Tübingen errichteten und erweiterten Institut der naturwissenschaftlichen und der medizinischen Fakultät," 1889. By permission.

 

at Tübingen he made most important contributions to the science, especially with regard to the physical and chemical properties of plant tissues, notably in osmosis and turgidity, and also in the transformations of energy within the organism. His laboratories and lecture room are thronged with students from all over the world, many of whom are Americans.

The present director of the institute and garden, Prof. Hermann Vöchting, succeeded Pfeffer in 1887. Prof. Vöchting may be said to be to some extent a representative of the modern idealistic school with which Braun, his old teacher, was identified. His work, however, resembles that of the idealists only so far as to exhibit the immense value of comprehensive discussions of the results of careful inductive inquiry, not only in the establishment of individual facts, but in the employment of these facts in their relations to the most general notions and their capabilities for the foundation of new and more comprehensive theories—a method of investigation productive of the highest results in all departments of biological science. One of the conclusions reached in this manner, which asserts the "polarity" of the plant cell, is at present beyond the general level of the subject. Polarity will doubtless be recognized as one of the most important physiological properties of protoplasm when the advance of the subject makes its appreciation possible. The researches of Vöchting have dealt principally

 

The Botanic Institute, View from Wilhelmstrasse.
After a photolithograph, by permission.

 

with the physiology of movement and what might briefly be termed physiological morphology.

The garden is located in the northeastern part of Tübingen in western Würtemberg, It lies at an elevation of about one thousand feet, on the plateau encircled by the Schwarzwald, in latitude 48° 30' north. Near it are hills covered with forests of pine, which rise two hundred and fifty to three hundred feet above it, while to the southward, twenty miles away, the Swabian Alps reach to a height of twenty-five hundred feet, in consequence of which the night temperature falls far below that of the day. A low winter temperature of -30° C, and a summer limit of 25° to 28° C, help to make a climate which resembles that of southern Michigan in many respects. The area inclosed amounts to about two and six tenths hectares of nearly level land on both sides of the banks of the Ammer, a small tributary to the Neckar. The grounds are planted in the system of Eichler, modified, however, to meet the ecological and æsthetic requirements. A small portion is devoted to aquatic plants, a second to an arboretum, another to anexperimental plot inclosed and accessible only to workers. In the entire garden the instinctive ability of the naturalist is shown in the selection of natural conditions for the specimens of the various flora represented, and the alpinum may be regarded as a triumph in the art of artificial culture.

The alpinum is laid out in the northwestern part of the garden on a rectangular plot of ground one hundred and ninety feet in length and nine feet in width, near a stone wall seven feet high and parallel to its length. On this plot are piled the rocks and soil necessary for the culture of plants, in an uneven ridge, which in one place is six feet in height. The materials used were principally the native stalactite limestone and gravelly soil and granite from the Black Forest, forty miles distant. The limestone is peculiarly suitable for the lower Alpine plants and lithophytes, furnishing, as it does, innumerable cavities for the reception of soil and secure foothold for plants which cling directly to the rock. It has been found that the species from the higher European Alps refused to grow on such rock, and hence the granite was procured for the section devoted to this group. The entire structure is in many respects an admirable imitation of an east-to-west mountain ridge. The northern side affords many shaded crevices, and more or less shade to the whole is given by a number of small trees near by.

The most difficult problems which have confronted the gardener in the construction and management of the alpinum have been those connected with the water supply. The water content of such rocky soils is of course extremely small and needs almost constant replenishment. In Nature this is done by water from the melting snows above. Here it has been accomplished by a system of branching pipes with many openings below and above the surface, and a flow is allowed during the greater part of the day. The drainage is carried away by cement conduits, and in one place forms an Alpine lake eight feet in length and five feet in width, which furnishes in its waters and on the overhanging cliffs admirable conditions for a very rich flora. Near the lake are growing several specimens of Edelweiss, which here becomes somewhat longer stemmed than on its native cliffs, or in the Alpine gardens where it is cultivated to satisfy the thirst of the tourist for mementoes of "hazardous" ascents.

Many of the Alpine plants are quite intolerant of lime salts and grow best on the granite rocks, but the water supply used here is taken directly from the city system and is very richly charged with these substances, and as a consequence the culture of some of the plants of the higher slopes is impossible. This difficulty might only be overcome at some cost by a system of tanks for the storage of rain water, which would furnish exactly the natural conditions for a large number of species.

It is somewhat surprising to learn that in this area of about two thousand square feet more than twelve hundred species are successfully cultivated, almost all of which are perennials. In some places three or even four kinds are grown on a square foot of actual surface—a striking example of a form of intensive cultivation. It must not be supposed, however, that none but Alpine species are grown. A glance at the labels will show

 

Corner of Lecture Hall; View from Garden. After a photograph.

 

that many are at home far southward in the temperate zone. It is interesting to note that all of the North American species of Cypripedium are grown here successfully. As a matter of fact the alpinum offers a wider range of conditions than any other method of cultivation, and in some form similar to that described might offer suitable conditions of growth for species fairly representative of the flora of a region extending across twenty degrees of latitude.

The glass houses are of the usual form, and include a palm house two hundred feet in length, to which are attached workrooms and the herbarium building. The immediate supervision of the cultural department of the garden is in the hands of the head gardener, who is provided with a commodious dwelling and office building near the arboretum. He has under his direction a force of men varying from eight to fifteen with the requirements of the season.

The institute is an oblong brick structure, one hundred and seventy feet in length by sixty-five in width, standing in the southeastern corner of the grounds. This building is two-storied in part, the second story being devoted to the use of the director and his family. The first floor accommodates the director's offices, private laboratory, and experimental rooms, dark rooms, laboratories for physiology and morphology, the lecture room, and a museum containing the Gaertner collection.

The laboratories are supplied with a set of physiological apparatus embracing the standard forms, a large number of which were originally designed to facilitate researches undertaken here in the last twenty years. The museum contains the von Mohl collection of microscopes, which represents the development of this instrument from the time of Joseph Gaertner to that of Hofmeister, more than one hundred years. The Gaertner museum contains the carpological collections of Joseph Gaertner, on which his work De Fructibus, etc., was based, in the labeled bottles as prepared by him. For greater safety these bottles were inclosed in larger bottles and labeled by von Mohl, and the thoughtful observer looks forward to the time when a third casing of glass will be added to protect the prized handwriting of von Mohl. In this museum are also to be found the dried specimens of hybrids and seeds, drawings, manuscripts, and published works of Karl Friedrich Gaertner, and a large number of preparations for the microscope made by von Mohl and Hofmeister. The commodious lecture room is provided with all necessary appliances for successful demonstrations—charts, prepared specimens, wood and paper models, etc.

The investigator who comes here to undertake the solution of some problem in botany meets a body of congenial workers whose earnest enthusiasm is quickly contagious. He is furnished with ample space in well-lighted rooms and any necessary apparatus. If it is necessary to construct temporary apparatus to carry forward his experiments, a stock of material is at hand and he may have the intelligent assistance of the "Hausmeister," who has had a score of years of experience in such work in this institute. If the problem requires the application of delicate or complex machinery, he may call to his assistance Herr Eugen Albrecht "Universitäts-mechaniker"—whose skill in designing effective apparatus for use in the physiology of plants and animals is known round the world. The library of the institute and that of the director contain a large number of works of the more prominent botanical authors, and a blank form properly filled will bring to his desk almost anything bearing upon his work from the library of the university, containing two hundred thousand volumes, in an hour or two. Outside the laboratories lies a garden stocked with an immense variety of well-grown plants representing great diversities of form and habitat, and presenting suitable material for the solution of a number of the more important open questions in the subject. Stretching away on every hand is the rich flora of the limestone hills, crested by coniferous forests. The subalpine vegetation of the Swabian Alps may also be reached by an excursion of a few kilometres.

The forests, lying within half an hour's walk of the garden, embrace examples of the royal, communal, and private systems

 

Group of Microscopes from the von Mohl Collection. The upright wooden stand on the right was used by Gaertner. The modern form on the left belonged to Hofmeister. The remaining stands were designed or used by von Mohl. After a photograph.

 

of management, and afford splendid opportunities for study in dendrology.

The most valuable part of the worker's experience, with such ample facilities at hand, however, is that which comes from the advice, encouragement, and suggestions of the director. Constantly engaged in the most laborious research for more than a quarter of a century, he has a vivid and sympathetic appreciation of the difficulties which beset the investigator, and his keen insight into the physiology of plant life leads him quickly to the solution of the problem in hand. His time and patience are unstintingly given to any who may have the slightest claim upon them, and the many times repeated assertion that the German professor gives a minor portion of his time only to his students is certainly ungrounded here. The writer is not acquainted with any American laboratory for botany in which the professor in charge devotes a greater proportion of his time to the student. In earlier times the Tübingen professors carried this devotion to the interests of the student to such a degree that it amounted to a fault, and published their own researches under the names of their students. This generous, unselfish, and high-minded attitude is an inheritance in the Botanic Institute at Tübingen, and is characteristic of the people among whom it is situated.