HETEROCHROMOSOMi: i >| MALE (>RK,IN IN ECHINOIDS. 1 5.; 



non-occurrence of such an element in Toxopneustes ey;^ has 

 been shown by Heffin r '10) and by further Mudyin my labora- 

 tory with this point in mind. I have been able to determine 

 that tin- hook haped chromosome i- pre-ent in hall of the 

 Toxopneustes eggs which have been fertilized \>\ IIi[>po> - rni. 



,' 



ABC 



! 



! i . in irniit vii-w. 



By this analysis of the subject it is th< -h>\\n i lliai tin- 



IK -iik--. ha; d rhr- mn -. mn- i~ |u-culiar t<> IIif)f)nn'. J that thi- 

 chnimii-i.nir i- i arrii-d b\ tin / ermatOZOa, and ; . 



that, -inc.- thi- !. -nn in i- tund in half i if the -trai-ht frrtili/i-d 



I 'I / ' / 



L 



I 



A TJ P 



/v * 







NIP In ink- |P! 



-and in halt nf tin 'iTtili/cd eggs it nni-t bt- prc-cni in 



but half i if the H'rrmat"/' 



V , .iiclu-i\i- ^lali-nu-nt can as \ et be made re-ardin^ the 

 number nf chromosomes in the-, eggs I'he --Id idea that the 

 xunatic number of chromosomes in echiimdi-rm- i- -it her ei-htei -n 



