52 The Science of Life. 



at all the levels of analysis, and that at none is there 

 anything approaching completeness. 



One of the roots of physiology is in the lore of the old 

 physicians. This was at first, doubtless, either empirical 

 Ancient or superstitious, but it began very early to 

 Physiology, take more rational form. Thus Hippocrates 

 (460-377 B.C.), who was a " priest-physician" at one of 

 the famous JEscu\a.pia.n hospitals or temples of health, 

 usually gets the credit for trying to place the study of 

 medicine on a scientific, as opposed to a superstitious 

 basis. The other root of physiology is to be found in 

 speculative attempts to formulate some theory of organic 

 life. These attempts oscillated between extremes of 

 materialistic and spiritualistic hypotheses, but it seems 

 hardly possible to speak of an observational basis before 

 the time of Aristotle. 



The interest of the Aristotelian physiology is twofold ; 



it represents an attempt to understand the activities of 



the body in their relations to one another, 



Aristotle. j . , i_ j i 



and it was to some extent based on observa- 

 tion. To one who had seen the punctum saliens (the 

 beating heart) in the embryo-chick within the egg-shell, 

 who knew of the parthenogenesis of bees and the quaint 

 discharge of an arm in cuttle-fishes, who discerned that 

 the foetus got its food-supplies from the maternal blood 

 through the umbilical cord, the functions of the body 

 were not likely to be treated of in the easy-going fashion 

 which characterized his predecessors. Yet his mixture 

 of truth and error is extraordinary. Aristotle connected 

 all the functions with the animal heat, which he believed 

 to be associated with the blood and centralized in the 

 beating heart. The blood is recuperated by the food in 

 the gut, is kept fluid by the heart's heat, is carried in 

 the pulsating vessels, and not only nourishes the organs, 

 but gives them mobility and sensitiveness; the urine is 

 derived from the blood flowing in the kidneys ; the brain 

 is bloodless and produces mucus; the sense-organs are 

 in the head so that they may not be overheated by the 

 blood ; the heart is the seat of the soul and its controlling 

 agencies. 



It is generally allowed that Galen (132-200 (?) A. D.) 



