The New Student's Reference Work/Anatomy

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The New Student's Reference Work (1914)
Anatomy
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Anat'omy. It is a common mistake to suppose that anatomy applies only to the bones; on the contrary, it includes the structure of both animals and plants. Just as the architecture of a house shows its plan of construction, so anatomy, or the architecture of animals and plants, shows how they are constructed, and with the higher animals this is a very complex thing. The physicians and medical men were the first to take an interest in the anatomy of the human body, because a knowledge of it is necessary for medicine, and it thus happens that the earliest observations in this line were directed toward making known the structure of the human body and of animals rather closely related to man in points of structure. Anatomical study, therefore, began with the most complex animals instead of with the simpler ones, and this led to many misunderstandings. It was so difficult in the early days to get an opportunity to study the human body that the pioneer anatomists were obliged to gain their knowledge by dissections of animals like the dog and occasionally of a monkey. Aristotle (B. C.384–322) and other ancients learned a great deal about anatomy in this way.

About B. C. 300, the dissection of the human body was legalized in the Alexandrian school, the bodies of condemned criminals being devoted to that purpose. But this did not become general, and anatomy continued to be studied mainly from brute animals.

Finally, in the early part of the Christian era, Galen (130–200 A. D.), became accepted as authority, from the 2d century, in which he lived, to the revival of anatomy in the 16th century. During the decline of intellectual life, in the dark ages, there was no progress. In the 14th century, observations were renewed, but no particular advance was made for about two centuries. Then a highly-gifted man of great intellectual power—Vesalius (1514–1564)—was born, who gave himself to the study of anatomy. Under his hands the science underwent a revival, and his work marks an epoch. In 1543, at the age of 29, he published a book (De Corporis Humani Fabrica), most beautifully illustrated, which is accepted as laying the foundations of modern anatomy. In this book he corrected many errors of Galen, and claimed that the knowledge of that anatomist had been gained from the bodies of apes and other brute animals, and not from man. Vesalius had with great difficulty procured the bodies of some criminals for his studies, and he reaped the displeasure of the authorities and of the Inquisition, by whom he was threatened. He found himself in controversy with his teachers and contemporaries, most of whom defended the authority of Galen, but in due course of time his position was triumphantly established and the authority of Galen overthrown.

Anatomy began now to assume more importance, and there arose famous teachers of the subject. The Italians were at this time in the lead—the prejudices against dissection in Germany, France and Britain prevented the development of the subject in those countries. The school at Padua became deservedly famous, and students were attracted to it from all over Europe and Britain. From England, William Harvey (1578–1657) found his way to Padua as a medical student. In the early part of the 17th century, he made an epoch in both anatomy and physiology by the demonstration (1628) of the circulation of the blood. Among the famous Italian teachers of the period were the leaders in anatomy: Vesalius, Fallopius and Eustachius (from whom is named the Eustachian tube). Thus in the 16th century human anatomy was well established.

The subject became broadened. Naturalists began to take more interest in animals and plants, and there gradually grew up those who compared the structure of higher animals with the simpler ones. These comparisons brought out so many resemblances and so many remarkable facts as regards construction, that anatomy, which seems at first a dry subject, became endued with great interest. Presently; it was discovered that insects have a most beautifully constructed organization; that they have delicately formed organs for digesting their food, with fine salivary glands, a remarkably beautiful nervous system, breathing tubes, etc. Thus there was opened a new world to anatomists. These studies in minute anatomy fascinated all who undertook them; and well they might, for there are no more beautiful illustrations in nature of delicate structures nicely adapted to the purposes of life. Malpighi the Italian and two Dutchmen, Swammerdam and Leeuwenhoek, were the leaders in this field, and the sketches with which they illustrated their studies excite our admiration even to-day. Malpighi and Leeuwenhoek also began to apply the microscope to anatomical study, and a new line of advance was started, involving minute or microscopic anatomy. The same kind of architectural study was extended to the other groups of lower animals, and a great fund of new knowledge was acquired. At the same period Malpighi, Grew and others laid the foundations of the knowledge of the minute structure of plants.

The interest of naturalists kept deepening, and finally, just at the beginning of the 19th century, the great Cuvier (1769–1832) founded the science of comparative anatomy. The men who have followed in his footsteps and made the work, in this particular line, more modern, are Meckel, J. Müller, Rathke and Gegenbaur in Germany; Richard Owen, Goodsir and Huxley in England; and Joseph Leidy and E. D. Cope in America.

Simultaneous with the work of Cuvier came that of his equally distinguished contemporary Bichat (1771–1802), who, while Cuvier was studying principally the organs, directed his attention to the tissues of which the organs are composed. Bichat took a step further than Cuvier. He founded the Department of Histology or Microscopic Anatomy of organs. This line of analysis was, in 1839–40, carried still further by Schwann and Schleiden, who showed that the tissues are composed of cells. All anatomy since 1840 has been greatly modified and influenced by this cell theory.

Having gained some knowledge of the construction of animals and plants, it is natural that the next step should relate to the process of building. Since it is known that all animals and plants start in a relatively simple microscopic rudiment—a seed or an egg—we wish to know, farther, something about the series of steps by which this simple rudiment is converted into the highly complex organism. This line of study is called Embryology or Development. As early as 1769, Wolff showed the true nature of development, viz., that it is an actual process of construction, and not simply the expansion of a preformed miniature, as was quite generally believed in his time. But Von Baer (1792–1876), is regarded as the founder of the modern ideas of development. He showed that all the organs and tissues in the bodies of animals proceed from three first-formed layers of cells or the germ-layers and that corresponding tissues come from the same one of the three layers in all animals above the very lowest. The facts of development, taken in connection with the doctrine of organic evolution, have greatly influenced the progress of anatomy. Comparative anatomy, especially, has been the gainer. The comparative structure of animals assumes new meaning when we understand that the higher animals are connected by a series of gradations with the lower ones, and that the higher animals present many fundamental features of resemblance to the lower ones in very early stages of their development.

This is, briefly, the story of the rise of anatomy. It shows how the study began with a narrow aim,—that of making known the structure of the human body for the use of medical men; then, after various vicissitudes, how it was broadened and deepened to include the structure of all living beings; and how, finally, the story of the development of life was added to that of its structure. Anatomy has thus come to be an important department of biology.

Let us now see what are its principal subdivisions: We must, of course, have descriptive and surgical anatomy for medical men. We must also have physiological anatomy to understand the workings of the organs. We must have microscopical anatomy in health, which is called histology, and in disease, which is called pathology.

The study of comparative anatomy is important to the zoologist and botanist. In these connections, it is usually called morphology, a name contrasted with physiology. In the broad sense, this includes the construction of all plants and animals from the simplest to the highest. Finally, we have anatomy for artists.

But it is all too large a field to be even systematically outlined here. For a knowledge of the facts of anatomy one must consult special books. Gray's and Quain's Anatomies are the ones most used at present by medical students. For comparative anatomy of vertebrates, the manuals of Gegenbaur and Weidershehn are recommended. For general morphology, Thompson's Zoology and Parker and Haswell's Text-book of Zoology are among the best. For comparative anatomy of invertebrates, see Lang's Text-book of Comparative Anatomy.

Wm. A. Locy.