THE CORRELATION BETWEEN CHROMOSOMES 

 AND PARTICULAR CHARACTERS IN HY- 

 BRID ECHINOID LARVAE 1 



PROFESSOR DAVID H. TENNENT 

 Bbyn Mawr College 



The student of genetics who bases his researches on 

 the development of echinoderms has become quite accus- 

 tomed to the criticisms of his friends to the effect that his 

 work can have little point until he can show them indi- 

 viduals of a second or a third generation, and he receives 

 these criticisms at their full value. 



Our ignorance on this subject has been clearly denned. 

 First, little is known of the inheritance in the adult 

 hybrids of the characters of the parent species, and sec- 

 ond, it is not known that these hybrids become sexually 

 mature. 



The ready acceptance of these ideas has blinded us, in 

 a measure, to the fact that for the solution of some of the 

 problems of heredity, the echinoderms offer material of 

 unusual advantage. The plants, insects and vertebrates 

 are peculiarly adapted for the elucidation of the later 

 aspects of heredity; the echinoderms are available for 

 information concerning the processes which occur during 

 and immediately after fertilization. 



In the course of this paper I shall show that we are 

 now in a position to predict certain characters in the 

 adult hybrids from a knowledge of the germ cells of the 

 ancestors and, granted the sexual maturity of the hybrid 

 adults, to predict the character of their germ cells. 



The evidence that I shall bring forward is based on a 

 study of chromosomes. The advantages afforded by 

 echinoderms for such a study, lie in the fact that not only 

 may we study the chromosomes during the divisions of 



*Read before the American Society of Naturalists, Princeton, 1911. 



