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PREFATORY NOTE 



THE design of this Text-book of Embryology, of which this is the 

 first volume, is to associate the structural development of embryos 

 with broad generalizations of what is known of their physiology. 

 Attention will be drawn, for instance, to the correlation between 

 the function of certain organs of a larva and its habit of life, and, 

 in a more general way, between function and habit and the course 

 of development. Reference will be made to some of the more 

 striking results obtained by Experimental Embryological research. 

 Attention will be drawn to gaps in our knowledge which indicate 

 promising fields for research. 



It is hoped that the interest of all students of Embryology will 

 thus be stimulated, and the practical value of these volumes, 

 especially for students of medicine, ensured. 



A second volume, by Professor Graham Kerr, in which the lower 

 Vertebrata will be dealt with, will follow as soon as possible, and 

 a third volume by Mr. Richard Assheton, on Mammals, will complete 

 the work. 



The Authors are responsible for the facts and generalizations 

 recorded, and to them is due all the credit which may be given 

 to the work. 



THE EDITOR. 



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