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 



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