Vlll PREFACE. 



With the exception of Figure 12, which is taken 

 from Dr. Burdon Sanderson's " Handbook for the 

 Physiological Laboratory," tLe illustrations have 

 been prepared expressly for this work ; they are 

 from the pencil of Mr. Collings. 



The methods employed in the practical study of 

 Embryology have been omitted ; they will be found 

 admirably given in the " Elements of Embryology" 

 of Dr. M. Foster and Mr. F. M. Balfour. 



UNIVERSITY COLLEGE, LONDON : 



November, 1876. 



