PREFACE TO VOLUME II. 



THE present volume completes my treatise on Com- 

 parative Embryology. The first eleven chapters deal 

 with the developmental history of the Chordata. These 

 are followed by three comparative chapters completing 

 the section of the work devoted to Systematic Embry- 

 ology. The remainder of the treatise, from Chapter 

 XIV. onwards, is devoted to Organogeny. For the 

 reasons stated in the introduction to this part the or- 

 ganogeny of the Chordata has been treated with much 

 greater fulness than that of the other groups of Metazoa. 



My own investigations have covered the ground of 

 the present volume much more completely than they did 

 that of the first volume ; a not inconsiderable proportion 

 of the facts recorded having been directly verified by 

 me. 



The very great labour of completing this volume has 

 been much lightened by the assistance I have received 



B. III. 



