1894] The Scope of Modern Physiology. 381 
for the science and art of medicine, it was to be expected that 
‘their investigations should have an “anthropocentric” bias 
and that physiology and medicine should be born and grow 
old together. Let a union so intimate be once established, let 
centuries of tradition surround and strengthen it and the sep- 
aration is not an easy process. With special reference to this 
question and at the risk of treading upon well-known historic 
ground, what has been in brief the history of animal physi- 
ology ? 
It is convenient to divide it with Preyer into five periods; 
the first four ending approximately with the dates 350 B. C., 
160 A. D., 1628, and 1837 respectively, the fifth extending to 
the present time. The last four periods are characterized by 
one or more prominent investigators, the second by Aristotle, 
the third by Galen, the fourth by Harvey and Haller, the fifth 
by Johannes Miiller. 
The beginnings of animal physiology were contemporane- 
ous with the speculations of the earliest natural philosophers 
and the labors of the earliest physicians. In Egypt, in China, 
in India, in Greece, the origins of the science are necessarily 
indefinite and, with the help of occasional fragments of his- 
torical fact, must be left to our imagination. The inclination 
toward self-study is an innate human characteristic and the 
more obvious facts of man’s bodily functions could scarcely 
have failed of notice. Something was doubtless learned from 
the bodies of men killed or wounded in battle, and from the 
“slaughter of animals for food. More precise observations were 
made upon sacrificial animals for purposes of divination. But 
facts thus obtained were necessarily isolated, and abundant 
Speculation was the distinguishing characteristic of the whole 
period. From its shadowy beginnings down to the death of 
Hippocrates and Plato, the theories that were held regarding 
the origin and nature of life, unsupported, as they T by 
observation and experiment, could not establish a science of 
vital action. Even Hippocrates himself, skillful as he was in 
the treatment of diseases, was no physiologist. 
~ At the beginning of the second period was Aristotle, the 
first systematic observer of natural phenomena. His knowl- 
