PREFACE, 
The issue of the present Volume may be considered as an 
attempt to supply what the Author has long considered to be 
a deficiency in the literature of this country,—that, namely, 
of an Educational Treatise on Animal Physiology, which 
should at the same time communicate to its readers the facts 
of greatest importance as regards their practical bearing, 
and present these in such a form as to place the learner 
in possession of the essential 'principles of Physiological 
Science. 
The Author has followed the general plan of the Treatise on 
Animal Physiology contributed by Professor Milne-Edwards, 
one of the most eminent Naturalists in France (in which 
country it is not thought beneath the dignity of men of the 
highest scientific reputation to write elementary books for 
the instruction of the beginner), to the “ Cours Elementaire 
d’Histoire Naturelle ” adopted by the French Government as 
the text-book of instruction in the Colleges connected with 
the University of Paris, which requires from every Candidate 
for its Degree of “ Bachelor of Sciences ” a competent know¬ 
ledge both of Animal and of Vegetable Physiology. He has 
also had at his disposal the admirable series of Illustrations 
prepared for that work, which, as a whole, are unsurpassed 
either in beauty or in exactness. 
In carrying-out this plan, however, the Author has entirely 
followed his own judgment; and has made so much more use 
b 
