SOME NEW TYPES OF CHROMOSOME DISTRIBU- 

 TION AND THEIR RELATION TO SEX. 1 



FERNANDUS PAYNE. 



INTRODUCTION. 



Since the discovery of the " accessory chromosome " in 

 Pyrrhocoris, by Henking, this chromosome or its equivalent has 

 been described in many other Hemiptera ( Paulmier, Montgomery, 

 Wilson and others) and also in many other tracheates Orthop- 

 tera (McClung, Sutton and others), Coleoptera (Stevens), Myria- 

 poda (Blackmail and Medes) and Odonata (Lefevre and McGill). 

 Wallace and Berry have also described it in the Arachnida. 

 Essentially, the " accessory chromosome " is a spermatogonial 

 chromosome, which is without a synaptic mate, and which divides 

 in but one maturation division. The end result is that one half 

 of the spermatozoa receive one more chromosome than the other 

 half. The spermatozoa are therefore dimorphic in respect to the 

 number of chromosomes. 



A second type of dimorphism of the spermatozoa was dis- 

 covered by Stevens ('05) in Tenebrio and by Wilson ('05) in 

 Lygaus, Ccenus and several other genera of Hemiptera, and was 

 afterward found by Stevens ('08) in the Diptera. In this type, 

 both classes have the same number of chromosomes, but differ 

 in that one class contains a large idiochromosome and the other 

 a small one. These observers showed that the class containing 



1 My material was taken in large part by Professor E. B. Wilson on his col- 

 lecting trip through the South and West, and it is due to this material that 

 I have been able to make this comparative study. I have also received much 

 valuable material from Rev. A. H. Manee, Southern Pines, N. C., besides 

 collections which I have made in New Jersey, Massachusetts and Indiana. 

 This material Mr. E. P. Van Duzee, of Buffalo, has kindly identified for me. 

 Throughout the entire work, I have been much indebted to Professor Wilson 

 for helpful suggestions and criticisms. I wish to thank Dr. Alexander 

 Petrunkevitch for the privilege of working in his private laboratory at Short 

 Hills, New Jersey, for five weeks during the spring of 1908. The U. S. 

 Bureau of Fisheries also extended to me the privilege of working in the 

 laboratory at Woods Hole, Massachusetts, during the summer of 1908. 



