vi PREFACE. 
of his own materials than of those supplied by the treatise of 
Professor Milne-Edwards, that the work may be regarded 
as almost entirely original. The present Edition, too, has 
undergone very considerable modifications ; the first chapter, 
which now contains a complete outline of the Elementary 
Tissues of the Animal Body, and the last, in which a com- 
prehensive sketch is given of the principal phenomena 
of Reproduction and Development throughout the Animal. 
Kingdom, having been entirely re-written and illustrated with 
numerous additional figures. In order to make room for the 
large amount of new matter now introduced (not less than 
one-fifth of the entire volume), the second chapter, contain- 
ing a General View of the Animal Kingdom, has been much 
abridged ;—a change the Author has the less regretted being 
obliged to make, since there are now before the public several 
excellent Elementary Treatises on Zoology, which had no 
existence at the time this volume originally appeared. 
Everyone who desires to see the study of Physiology duly 
appreciated as a branch of General Education, must feel 
gratified at the progress which has been made of late years in 
the public recognition of its value. The University of Londo 
led the way, by the introduction of Animal Physiology into 
the programme of study to which all Candidates for its Degre 
of Bachelor of Arts are required to conform. The Universi 
ties of Oxford and Cambridge have since admitted it as on 
of the subjects which Candidates may select for their Bachelo 
of Arts Examination, and in which they may obtain Honours 
And in many of the large Public Educational Institutio 
with which this country is now so abundantly furnished, i 
forms a part of the regular course of instruction. 
It has. been the Author's steady aim, not merely to adap 
his treatise to the wants of those who wish to acquire 
general knowledge of the principal facts and doctrines o 
Physiological Science, but also to render it suitable to that 
