42 THE BIDDLE OF THE UNIVEESE. 



In human physiology, as well as in anatomy, the 

 great system of Galen was for thirteen centuries the 

 Codex aureus, the inviolable source of all knowledge. 

 The influence of Christianity, so fatal to scientific 

 culture, raised the same insuperable obstacles in this 

 as in every other branch of secular knowledge. Not 

 a single scientist appeared from the third to the 

 sixteenth century who dared make independent 

 research into man's vital activity, and transcend the 

 limits of the Galenic system. It was not until the 

 sixteenth century that experiments were made in 

 that direction by a number of distinguished physicians 

 and anatomists (Paracelsus, Servetu-, Vesalius, and 

 others). In 1628 Harvey published his great dis- 

 covery of the circulation of the blood, and showed 

 that the heart is a pump, which drives the red 

 stream unceasingly through the connected system 

 of arteries and veins by a rhythmic, unconscious 

 contraction of its muscles. Not less important 

 were Harvey's researches into the procreation of 

 animals, as a result of which he formulated the 

 well-known law: " Every living thing comes from 

 an egg" (omni vivum ex ovo). 



The powerful impetus which Harvey gave to physio- 

 logical observation and experiment led to a great 

 number of discoveries in the sixteenth and seven- 

 teenth centuries. These were co-ordinated for the 

 first time by the learned Albrecht Haller about the 

 middle of the last century ; in his great work, 

 Elementa Physiologice, he established the inherent 

 importance of the science, independently of its relation 

 to practical medicine. In postulating, however, a 

 special " sensitive force or sensibility " for neural 

 action, and a special "irritability" for muscular 



