18 GENERAL PHYSIOLOGY 



The analysis of the phenomena of life also necessitates as a pre- 

 requisite an adequate knowledge of physics and chemistry. Without 

 these sciences physiological progress would indeed be slow or even 

 impossible. This fact accounts in a way for the almost exclusive 

 position which anatomy has enjoyed until comparatively recent 

 years. As the acquisition of gross structural data is not at all depend- 

 ent upon the development of the supplementary sciences, anatomy 

 has been able to advance practically without restrictions of any kind. 

 At the close of the nineteenth century it had thus acquired an almost 

 dominating position. On the functional side, scarcely any progress 

 was made until the beginning of the sixteenth century, when Paracel- 

 sus (1493-1541) attacked the doctrines of Galinus (131-200) and 

 developed a physiological system of his own. Greatly aided by the 

 anatomical discoveries of Vesalius, Eustachius, Faloppio and Serveto, 

 it was left to Harvey (1578-1657) to unravel the secrets of the circu- 

 lation of the blood. This discovery put an end to speculative physi- 

 ology and initiated experimental physiological methods. Harvey, 

 moreover, propounded a doctrine which was destined to exert a pro- 

 found influence upon the development of modern physiology, namely, 

 his doctrine "de generatione animalium." In recent years this work 

 has dominated our views regarding the origin of animal life arid has led 

 to the dictum of "omne vivum ex ovo." 



The seventeenth century is a memorable one for physiology, 

 because it produced a Copernicus, a Galileo, a Descartes, a Boyle 

 and a Newton, thus furthering our knowledge of physics. Of scarcely 

 lesser importance, however, is the construction of the compound 

 microscope which made the histological discoveries of Leeuwenhoek 

 (1632-1723), Malpighi (1628-1694) and Swammerdam (1637-1685) 

 possible. Then followed Albrecht v. Haller (1708-1777) who not 

 only greatly promoted the experimental side of physiology but also 

 combined the data then known into a homogeneous whole and thus 

 gave an independent existence to our Science. At about this time 

 were made the far reaching chemical discoveries of Priestley (1773- 

 1804), Lavoisier (1743-1794) and Girtannei (1760-1800). 



The period from 1800 to about 1860 is commonly regarded as 

 the renaissance period of physiology. It is dominated by such men 

 as Johannes v. Miiller (1801-1858) and Johannes Purkinje and, on 

 the chemical side, by Wohler (1800-1882) 1 and v. Liebig (1803-1873). 

 Physiology at once began to profit by the discoveries in chemistry, 

 because they found immediate application in the investigations of 

 problems connected with respiration, digestion and secretion. From 

 this time on physiology shows two tendencies, namely a physical 

 and a chemical. Very fortunately, however, this division has re- 



1 Mention is usually made of Wohler, because he succeeded in 1828 in producing 

 urea synthetically. In reality, however, this synthesis was preceded by several 

 others, namely, by that of alcohol (Hennel), that of acetic acid (Dobereiner, 

 1822) and that of oxalic acid (Scheele, 1776). 



