44S E. ELEANOR CAROTHERS 



reported, so far, are those in which the homologues differ mark- 

 edly in size. The first was the work of the writer which ap- 

 peared in 1913. giving data showing the alternative distribution 

 oi the unequal dyads oi one tetrad in relation to sex hi certain 

 Oedipodinae. Three hundred first spermatocytes were counted; 

 in 51.3 per cent the larger dyad was going into the same second 

 spermatocyte as the accessory, and in 4S.7 per cent the smaller 

 dyad was accompanying the accessory. Shortly afterward a 

 paper by Voinov 14 appeared, giving like results and an 

 essentially similar conclusion from a study of Gryllotalpa 

 vulgaris. 



Wenrich, hi 1914. reported similar results from a count of 

 four hundred and seventy-two first spermatocytes Of Phryno- 

 tettix magmas where a tetrad with unequal dyads is also pres- 

 ent. And lastly. Robertson {15), in an addendum to a paper 

 in which he reports an unequal pair oi chromosomes in Tetti- 

 gidea parvipennis and in Acridium granulatum. states that these 

 unequal pairs agree with the one in my material in regard to the 

 distribution of their dyads in relation to the accessory. These I 

 believe are the only instances so far reported where the chromo- 

 somes derived from different parents could be followed in the 

 germ cells and their distribution determined. 



It is to this problem of tracing the segregation of certain well 

 marked homologues in given individuals of the species studied 

 and then of determining the combinations actually present in a 

 considerable number of individuals of these species that I wish 

 to devote this paper. My study has been confined to the meta- 

 phases, but a knowledge of the behavior of the dissimilar homo- 

 logues during synapsis is essential to my conclusions. As this 

 problem was aside from my general plan, and directly in line 

 with Dr. "Wenrich's work, he kindly undertook its solution. 

 In a paper now in press he shows that the process of synapsis 

 and tetrad formation is the same for the heteromorphic tetrads 

 as for the homomorphic ones, whether the latter have terminal 

 or nonterminal fiber attachment. 



