viii ANIMAL PHYSIOLOGY. 
As so large a proportion of those who enter upon the 
study of medicine begin their career without any adequate 
preparation in general biology, the subject, as presented in 
this work, will, let me hope, meet an actual need, and prove 
helpful in attaining a broad and sound view of the special 
doctrines of biology. 
It is scarcely necessary to remark that clinical and path- 
ological facts have not been introduced with the view of 
teaching either clinical medicine or pathology, but to indi- 
cate to the student how his physiology bears on his profes- 
sion, and how the above-mentioned subjects throw light upon 
physiology proper and lend interest to that subject. 
My aim has been to make the book, from first to last, 
educative; and, retaining a vivid recollection of the severe 
strain put upon the memory of the medical student by our 
present method of crowding so much into at most four years 
of study, an attempt has been made to avoid overloading the 
book with mere facts or technical details, as well as to pre- 
’ sent the whole subject in as succinct a form as is compatible 
with clearness. Recognizing, too, the very shifting character 
of physiological theories, the latter have generally been pretty 
well kept apart from the actual facts. 
It is hoped that the abundance of the illustrations will 
prove more acceptable than would lengthy treatment of sub- 
jects in the text, for, if the matter of a book is to be digested 
and assimilated, either by the student of general biology or 
by the hard-worked medical student, it must not be bulky. 
The illustrations have been chosen from the best available 
sourees, and the authorship of each one duly acknowledged 
in the body of the work. Several original diagrams, such as 
I find exceedingly useful in my own lectures, have been in- 
troduced. ; 
This book is really an embodiment of my own course of 
lectures, as given during the past two years more especially, 
and with the highest satisfaction, I think it may be said, to: 
both students and teacher. 
I have unbounded confidence in the plan of the work, and 
