350 



Comparative Anatomy — Its History, Aim, and Method 



recapitulation, so strained the theory as to tend to bring it into dis- 

 repute. If, however, evolution is to be accepted at all, such things as 



Fig. 285. Diagrams showing structural 

 similarity of a coelenterate and a gastrula. 

 (A) Hydra, longitudinal section. (B) Gas- 

 trula, axial section. (A) Archenteron, pro- 

 spective digestive cavity; (BP) blastopore; 

 (E) enteric (digestive) cavity; (EC) ecto- 

 derm; (EN) endoderm; (M) mouth; (T) 

 tentacle. (Courtesy, Neal and Band: "Chor- 

 date Anatomy," Philadelphia, The Blakiston 

 Company.) 



transitory pharyngeal clefts, aortic arches, and notochords would 



seem to be open to no more reason- 

 able explanation than that they 

 are due to long-range inheritance. 



Of the two indispensable allies 

 of Comparative Anatomy, Em- 

 bryology owed its rapid advance 

 in the latter part of the nineteenth 

 century largely to F. M. Balfour 

 (1851-82) in England and, in Ger- 

 many, to Wilhelm His and, a little 

 later, Oskar Hertwig. In America, 

 the work of Louis Agassiz (1807- 

 73 : Harvard University ; founder of 

 the Museum of Comparative Zo- 

 ology) on the embryology of the 

 turtle was of permanent signifi- 

 Fig. 286. Louis Agassiz (1807-73). can ce. Outstanding figures in the 



last two decades of the century 



were W. K. Brooks (Johns Hopkins University), C. S. Minot 



