The controversy concerning the early develop ment of the human body was renewed during this period. The weight of authority was over whelmingly in favor of the theory of preforma tion, notwithstanding the absurdities to which it committed its advocates. Its most earnest supporter was Haller (170S-77) (q.v.), professor at Gottingen, a man of remarkable learning and indefatigable research, who did much to further exactitude in anatomical knowledge, and was the leading physiologist of his time. He made many anatomical discoveries in all parts of the body, and finally overthrew the doctrine of "animal spirits," which had ruled all investigations of the nervous system since the days of Hippocra tes. He declared, however, that the body of our primitive mother Eve must have contained in miniature all individuals of the human race that had existed since her time and that were hereafter to exist! This was the less excusable, as Kaspar Friedrich Wolff, a young medical stu dent, bad published in 1759, as his graduation thesis, a remarkable essay, the Theoria Genera tionis, in which he showed by accurate and con chi-sive observations that the organs of the body are developed from membranous sheets (the blas toderime membranes), and not from preformed rudiments. He even anticipated the cell-theory of the next century by stating that these mem branes are themselves composed of globules (cells). Wolff made many other important in vestigations, and his name has been perpetuated in that of the \\IOUlian body or primordial kid ney. Such was the opposition with which his views were received that he was unable to obtain a professorship in Germany and went to Russia. It was not until A:lecke] called attention to his work in 1812 that his merits were fully recog nized.
Aristotle, Enstachio, and Fallopio had sur mised that the organs of the body might be composed of simpler elements; Boerhaave (1663 1738) supposed that everything could lie reduced to vessels and fibres; Haller (1708-77) classified structures according to their properties: Bonn (173S-1818) considered that membranes are the anatomical of structure. It remained, however, for Bichat (1771-1802) to establish clearly the doctrine that the body with all its organs is made up of a small number of simple tissues. This he did by an examination of their chemical, physical, and vital properties, dispens ing wholly with the use of the microscope, then a very imperfect instrument. He applied these views to the elucidation of the anatomy of organs affected by disease, a subject previously studied by Morgagni (1652-1771) and by John Hunter (1728-93). Bichat's death, at the early age of thirty-one, caused by imprudent exposure in the dissecting-room, was a great loss to ana tomical science.
The science of chemistry had now advanced to a point where it could throw much light upon the composition of the animal body. Four great organic gases had been discovered: carbon di oxide (imperfectly known to Van Helmont in 1640) by Black in 1757, hydrogen by Cavendish in 1766, nitrogen by Rutherford in 1772, oxygen by Priestley in 1774. Lavoisier (1743-94)
showed the importance of all these gases to the animal economy. Fou•croy (1755-1809) was practically the first to investigate the composi tion of organic products.
The investigation of the human body by so many competent and careful observers gave a new scope to anatomical teaching. It was seen that no proper knowledge of anatomy or surgery could be obtained without the use of the cadaver. At first, legal enactments and social ostracism were directed against those who practiced dissec tion; but on the Continent of Europe public dis sections were frequently held from the time of Vesalius, and as men of commanding intellect like Malpighi, Stensen, Boerhaave, Morgagni, Bichat, Hunter. and many others devoted themselves to the pursuit of anatomy, the social stigma was gradually removed. On the Conti nent, laws were early enacted by which the bodies of prisoners and paupers were turned over for anatomical purposes. In Great Britain, how ever, this was not done, and bodies were quite commonly obtained by robbing graves. When, in 1827, the University of Edinburgh made dissection compulsory, and this example was fol lowed by the other large schools in the United Kingdom, the demand for cadavers became so great that it was practically impossible to sup ply it without breaking the law. A 'set of ruf fians known as "resurrectionists" became estab lished in every large city, and no cemetery was safe from their depredations. In Edinburgh two scoundrels named Burke and Hare made a business of enticing poor and friendless persons into their haunts, smothering them, and selling their bodies to the medical schools for dissection. Similar cases were those of Bishop and Williams in London. A remedy for this was found in an anatomy act passed in 1•32, which legalized dis section, and authorized the uce of available material under certain restrictions.
Improvements in the microscope made about 1824 gave a new impetus to research. Earlier observers (Hooke, 1665: Grew and Malp4.1dii, 1671; Wolff, 1759) had dimly surmised that organic forms were composed of elementary units, but Schwalm, in 1839, was the first to demonstrate this for animals in a satisfactory manner. Observations by Von Mohl. Furkinje, Leydig, Virchow, and Max Schultze soon placed this fact beyond cavil, and thus was established the celebrated cell-theory, which de clared all organized beings to be composed of essentially similar minute units. This led to great improvements in microscopical technique and the investigation of the chemical properties of cells. Stilling invented section cutting in 1842; Gerlach, carmine staining in 1858; Reck linghausen, silver staining in 1860; Waldeyer, double staining with aniline dyes in 1863, and Golgi, bichromate of silver staining in 1873.