PREFACE TO VOLUME 11. 



The present volume completes my treatise on Compara- 

 tive 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 Embryology. The remainder 

 of the treatise, from Chapter XIV. onwards, is devoted 

 to Organogeny. For the reasons stated in the introduction 

 to this part the organogeny 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 from 

 my friends and pupils. Had it not been for their co-opera- 



B. E. 11. 6 



