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 Eeproduction 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 London 

 led the way, by the introduction of Animal Physiology into 

 the programme of study to which all Candidates for its Degree 

 of Bachelor of Arts are required to conform. The Universi- 

 ties of Oxford and Cambridge have since admitted it as one 

 of the subjects which Candidates may select for their Bachelor 

 of Arts Examination, and in which they may obtain Honours. 

 And in many of the large Public Educational Institutions 

 with which this country is now so abundantly furnished, it 

 forms a part of the regular course of instruction. 



It has been the Author's steady aim, not merely to adapt 

 his treatise to the wants of those who wish to acquire a 

 general knowledge of the principal facts and doctrines of 

 Physiological Science, but also to render it suitable to that 



