EMBRYOLOGY OF THALASSEMA MELLITA 



221 



no longer equivalent. This idea has been clearly expressed by 

 Wilson in a discussion of a similar state of affairs. He says : ^ 

 *• The old building pattern was still retained but adapted to a 



emmL 



p 



Fig. 9. 



new use, precisely as has been the case with the evolution of 

 larval or adult organs, such as the branchial or aortic arches 

 and the limbs." Nevertheless, until we know more about the 



1 Wilson, E. B., " Cell- Lineage and Ancestral Reminiscence," Wood's Holl 

 Biol. Lectures, 1898, p. 39. 



