530 



PROCEEDINGS OF THE NATIONAL MUSEUM 



in obscurity, but he supports the view that the aortic vessels form in 

 situ and are not the result of a "budding" or outgrowth from the 

 heart nor a product of "migration," but rather are independent in 

 origin and formation from the heart. Hyman (1942) asserts that a 

 tubular cavity arises on either side (in the embryo) in the splanchnic 



a.a. 



r.av X^7/^?^^ 



=>j[o 



c.ir. C.c. 



^^, 



/ 



Figure 108. — For explanation see facing page. 



