388 The American Naturalist. [May, 
medical boundaries. It has long since ceased to be a purely 
medical and anthropological science; it has become a biologi- 
cal science. Human physiology, like human anatomy, will 
necessarily always form one of the foundation stones ofa 
medical training, and perhaps the most important one. But 
human physiology is but one branch of a science as broad as 
are the domains of protoplasm. Man’s body isa machine, but 
it is a machine that has had a history. It is an achievement 
to learn to know the mechanical, chemical, and physical laws 
of this most complex of vital mechanisms. But the task of 
the physiologist does not end here—I should say it does not 
begin here. To know the action of the mechanism without | 
its history is not only short-sighted, it is impossible. Thisis 
being recognized and a school of general and comparative — 
physiologists is arising. During the present period, then, — 
beside its great advance along the older lines, our science has 
begun a development along broader biological paths. It has . 
won a place as an independent, pure natural science. More 
and more are its claims to admission to Pure Science and Phil 
osophical faculties being recognized. It should be placed 
and will be placed by the side of chemistry, physics, and the : 
morphological division of biology. I do not think it mere 
gerated statement, that the tendency of biological thought at 
present is toward extraordinary activity along physiol 
lines. 
(To be continued.) 
