74 THE MAIN CURRENTS OF ZOOLOGY 



does eminent service. Up to this time the investiga- 

 tions of the embryology of animals, Both inverte- 

 brates and vertebrates, had resulted in a vast ac- 

 cumulation of monographs and scientific memoirs. 

 These publications were scattered in technical 

 periodicals, in the special publications of learned 

 societies, etc. 



Balfour gathered these researches, read, digested 

 and published the results in a unified picture of the 

 science of embryology. He clarified as well as 

 unified the subject and produced a comprehensive 

 book on comparative embryology that contained the 

 substance of what was known regarding the develop- 

 ment of all animals from the lowest to the highest. 

 Balfour was especially gifted with the power of dis- 

 criminating analysis and charm of expression. His 

 book, of priceless value to embryologists, was pub- 

 lished in two volumes, 1880-1881, under the title of 

 Comparative Embryology. 



Just after completing this monumental work while 

 on a journey to the Alps for recuperation he met his 

 death by slipping with his guide from one of the 

 Alpine passes. 



Since 1881 the science of embryology has devel- 

 oped rapidly. There has been great refinement of 



