PREFACE. vii 
By frequently calling attention, as has been done through- 
out, to actually discovered or possible differences in function 
for different groups of animals, it is believed that the student 
will become possessed of a spirit of caution in drawing con- 
clusions that will fit him the better for the hospital ward in 
another respect, viz., that he will be prepared for those indi- 
vidual differences actually existing, and which seem to have 
been largely ignored in so many works on physiology, with 
the natural consequence that the student, not finding his 
physiology squaring with the facts of the clinique, and not 
being prepared for the situation, the result is disappointment 
and disgust, instead of the actual continuation of the study, 
especially as human physiology. 
With a view of widening the student’s field of vision, sec- 
tions, under the heading “Special Considerations,” have been 
introduced, which it is hoped will not fail to interest and 
stimulate. 
Most teachers of experience will welcome the summary 
with which each chapter concludes. In connection with no 
subject perhaps can the art of generalizing be better taught 
than with physiology, and to this end these brief synoptical 
sections will, it is thought, prove helpful. 
Systematic instruction in either macroscopic or microscopic 
anatomy has not been undertaken—in fact, can not be at- 
tempted, it is believed, except at the expense of physiology 
proper—in a work of moderate compass. At the same time 
attention has been called to those points which have a special 
bearing on each function, and a number of illustrations have 
been inserted with this object in view. 
The introduction of the subject of development at so early 
a stage is a departure that calls for a word of explanation. 
An attempt has been made to use embryological facts to 
throw light upon the different functions of the body, and 
especially their relations and interdependence. It therefore 
became necessary to treat the subject early. It is expected, 
however, that the student will return to it after reading the 
remaining chapters of the work. 
