In 1661 Malpighi, who was in the habit of manufacturing his own microscopes, was able, by aid of one of these instruments, to exhibit the blood, loaded with its corpuscular bodies, passing rapidly from one capillary vessel to another in the frog’s lung. Then in 1683 Guillaume Molyneux, in 1690 Anton van Leeuwenhoek, and in 1697 William Cowper, witnessed the same phenomenon in warm-blooded animals. Among the other anatomists of this period who contributed in varying degrees to our knowledge of the minute anatomy of the different tissues and organs the following deserve to be mentioned: J. Riolan (1577–1657), Boselli of Naples (1608–1679), Lower of Oxford, England (1631–1691), Vesling of Minden, Germany (1598–1649), Regnier de Graaf of Delft, Holland (1641–1673), who gained so great distinction by his accurate description of the ovarian follicles (“Graafian follicles”); and James Douglas (1676–1742), the English anatomist, who ascertained and described the precise limits of the peritoneum.
Of all the men whom I have mentioned above, Malpighi and Leeuwenhoek are probably the best known to our readers for the large number and important character of the contributions which they made to microscopic anatomy. The list of Malpighi’s achievements, for example, includes the following, in addition to the demonstration of the blood in actual circulation, as already mentioned: contributions to our knowledge of the finer structure of plants; the demonstration of the minute anatomy of the skin (“rete mucosum” or “rete Malpighi”); the amplification of our knowledge of the structure of the teeth; the discovery that the lungs are composed to a large extent of terminal vesicles, the walls of which are richly supplied with blood-channels.; the demonstration that certain glands possess an acinous structure (i.e., an outlet channel springing from numerous small sacs, the whole group resembling a cluster of grapes); more complete details regarding the structure of the spleen and the kidneys (“Malpighian bodies or corpuscles”); additions to our knowledge of the structure of the white and the gray substances of the brain and the demonstration that fibres from the spinal cord pass on into the brain; the declaration that the papillae of the tongue are organs of taste and the papillae of the skin are organs of the sense of touch; and not a few other contributions of greater or less importance. During his long life Anton Leeuwenhoek (1632–1723) of Delft, Holland, made a great many additions to microscopic anatomy, some of the more important of which are the following: he was the first to discover and to describe the many varieties of Infusoria (the animalcules found in stagnant collections of water); to him is also due the credit of first observing the faceted arrangement in the eyes of insects; he made original investigations into the origin and mode of development of several species of the lower organisms; he was the first to observe the canaliculated mode of construction in bone, and he also noted the existence of the so-called bone-corpuscles (afterward rediscovered and more accurately described by Purkinje); he discovered the striated condition of the bundles of muscular fibres, and was also the first person to teach the doctrine that the growth of muscles is effected by an enlargement of the primitive bundles of fibres and not by a multiplication of these structures; he taught further that muscle-substance consists of numberless small spheres; he was the first to describe the crystalline lens as a structure composed of fibres which are arranged in layers or sheets; in association with Guillaume Molyneux he studied, under the microscope, the speed with which the blood-current travels in the blood-vessels; he made valuable observations on the nature of the spermatozoa; and, finally, the very first studies in bacteriology appear to have been made by Leeuwenhoek. As a result of his discovery of “round, rod-shaped, thread-like and corkscrew-shaped bacteria” between the teeth of a human being, the theory was set forth that probably many diseases owe their origin to such “little animals.”[75]
The same idea, as will be shown farther on, occurred to the distinguished medical practitioner of Verona, Italy,—viz., Fracastoro,—one hundred years earlier (1546). Leeuwenhoek, it should here be stated, possessed a very great advantage over his rivals in the field of minute anatomy, for he was in the habit of using, in his investigations, microscopes which he himself had made, and which magnified from 160 to 270 diameters, whereas those utilized by the others were capable of magnifying, at the maximum, only 143 diameters. While a large part of the work which he performed shows plainly that he was a skilful and careful anatomist and endowed with good mental powers, Leeuwenhoek nevertheless manifested certain mean traits of character. Daremberg says that these “consisted in his disposition to conceal his technical methods from his associates, and in his jealousy of others—as manifested, for example, toward Leibnitz, who had established a similar laboratory for research work in minute anatomy. These traits of character showed that fundamentally he was not a true lover of science, but rather an artisan. And yet, with all these faults, he does not appear to have placed an inordinately high value upon his discoveries or to have been unreasonably sure of the correctness of his conclusions.” The first monograph published by Leeuwenhoek bears the date 1673. It is a study of the minute anatomy of the bee’s sting. He was the first to declare that the blood is the nutritive fluid par excellence, and that it is to be found in the entire series of organisms belonging to the animal kingdom. He divided blood into two parts—the red, or the solid portion, and the serum. The corpuscles which float in the serum and give to the whole fluid its red color, are called by him “particles,” in the case of blood from birds, reptiles and fishes, and “globules” in that from quadrupeds. He employed this term “globules” because he believed that these bodies were exactly spherical in shape. According to Daremberg, Leeuwenhoek’s studies cover the entire field of human histology, and his findings are for the most part correct.
The Founding of Organizations for the Advancement of Medical Science.—During the seventeenth century there were formed a number of associations which had for their object the promotion of scientific knowledge, and these organizations contributed greatly to stimulate original researches in anatomy and physiology and to secure accuracy in the published results. Perhaps the most important institution of this kind was the French Académie des sciences, which was founded in 1666, and which deserves the credit of having taken a very important part in the perfecting of our knowledge of anatomy and physiology. The Royal Society of London, founded in 1645, possesses a splendid record of valuable work accomplished. The following organizations also deserve to be honorably mentioned in this place: the Accademia dei Lincei at Rome, founded in 1603; the Académie des Curieux de la Nature, 1652; and the Accademia del Cimento, founded at Florence in 1657. New universities were also founded in Germany.
During the second half of the seventeenth century there were three French physicians who deserve credit for the excellence of the work which they did in the departments of anatomy and physiology, viz., Vieussens, du Verney and Dionis.
Raymond Vieussens (1641–1716), a native of Rovergue, was Professor of Anatomy at the University of Montpellier, in Southern France. Some idea of the extraordinary industry displayed by this anatomist may be gained from the fact that he is credited with having dissected more than five hundred bodies. His more important published works relate to the heart, the nervous system and the structures of the organ of hearing. Pagel speaks of him as being entitled to the name of founder of the pathology of diseases of the heart.
Jean Guichard du Verney (1648–1730), who held the Chair of Anatomy in the University of Paris, gained a large part of his fame as an anatomist from the excellence of his investigations into the complicated structures of the internal ear.
Pierre Dionis, who died in 1718, was Demonstrator of Anatomy and Surgery at the Jardin du Roi in Paris during the latter part of the seventeenth century and early part of the eighteenth. In 1690 he published a treatise on anatomy which remained the standard book on this subject for a number of years. In course of time it was translated into the Latin, English, German and Chinese languages.
Dissecting Made a Part of the Regular Training of a Medical Student.—The opportunities for dissecting human bodies varied greatly in different parts of Europe during the period of which I am now treating. Vieussens, as we have just seen, dissected no fewer than five hundred bodies during his long professorship at Montpellier; and Joseph Lieutaud, Professor of Anatomy at Paris, dissected more than twelve hundred bodies during the continuance of his connection with that institution. So far as I have been able to learn from my examination of the literature, the professors and their immediate official assistants were the only persons who had, up to this time, derived the principal benefits that flow from work of this nature; the students merely listened to the instructor’s remarks upon the objects which had previously been exposed to view by dissection. But toward the end of the period—a little before or shortly after the beginning of the eighteenth century—facilities were provided in some of the medical schools, and before long in all of the leading ones, for the students themselves to participate in this highly important part of a physician’s education. The value of such training was emphasized by the statement made by the English philosopher, John Locke (1632–1704), toward the end of his life, viz., that all human understanding is based upon experience. He wrote that at birth the human soul is like a clean sheet of paper upon which all the objects perceived by the senses are recorded as experiences, and there they remain until by the aid of reflexion—i.e., by the aid of the understanding, which Locke calls the inner sense—they are combined into conceptions or ideas. Locke, it should be remembered, was educated as a physician, but he never took his degree, nor did he ever practice medicine.
The first stimulating effects of the Renaissance upon the devotees of the science of medicine were felt in Italy toward the end of the fifteenth century, and these effects rapidly gained in intensity during the following century. First France and afterward Switzerland, Belgium, Holland and England were almost simultaneously brought under the same influence; and in all these countries the students manifested a remarkable eagerness to acquire all the knowledge they possibly could. In Germany, however, the influence of the Renaissance did not make itself felt until a much later date, and the thirst for knowledge was very much slower in developing than was the case in any of the other countries mentioned. Thus Puschmann, in his “History of Medical Education,” makes the following statement which shows clearly that in Germany the university students of that period must have been a very rough set of men: “In 1625 the Senate of the University of Leipzig was obliged to warn its students that they must cease disturbing wedding festivals and handling the guests roughly, that they must no longer make obscene remarks to married women and maidens, etc. And in 1631 a physician named Lotichius, in writing to a friend, made the statement that ‘in our German high schools the students seem to prefer strife to the reading of books, daggers to copy-books, swords to pens, bloody encounters to learned discussions, incessant boozing and noisy reveling to the quiet pursuit of their studies, and public-houses and brothels to students’ work-rooms and libraries.’” In 1660 the students at Jena, on one occasion, carried on a regular battle with the police, and as a result of this encounter several persons were killed. In the light of this evidence, therefore, it is not surprising that the science of medicine made comparatively little advance in Germany until after the eighteenth century was reached.