No. 647] SHORTER ARTICLES AND DISCUSSION 571 



agents. Those which lived to produce young gave rise exclu- 

 sively to normal young, indicating that genetic changes were 

 not responsible for the abnormal heads. However, in view of 

 the known inheritance of eyelessness in cave arthropods and 

 vertebrates and in Drosophila melanogaster, it seems of interest 

 to examine each case of profound eye modification in crusta- 

 ceans and elsewhere to gain information on the origin and in- 

 heritance of any possible mutation of this character.^ 



ARTiirR M. Baxta 



Cold Spring Harbor, L. I. 



CROSSING-OVER INVOLVING THREE SEX-LINKED 

 GENES IN CHICKENS 

 In the course of the last year several crosses of chickens 

 carried out at the genetics station at Anikovo (near Moscow) 

 have made it possible to observe crossing-over in this form. The 

 genes "suke," ''tuge" and "trage" were studied. The first, 

 suke, retards the development of feathering ni the chicks, so that 

 at the age of 1 to 1.5 months they have verv small tails. Tlie 

 development of tlio wings, too. is verv slow. The izvncs traiJre 



The geiifs suke Ihlic ;iiu1 trage are all present together lu the 

 Phmouth R(tks 11, Uu^suiii Oiloff chukens lia\e none of 

 these cenes. a condit ion which mav bo expressed ;is asnkr-atug.'- 

 atrage. All those gfMu«s ;ire sex-lmkod. and tlicrotoi-e are trans- 

 mitted \Mth compkt( Imk.itr.' tir.ni ni.-thd to son Tlie cio-^s 



