ARE PARTICULAR CHROMOSOMES SEX DETERMINANTS? 3 



the sex character i- repre-ented in the chromosorn< Net in 



another paper (1909 that appeared simultaneously, Su-ven- 

 \vri' \- to tin.- fact that the- la^in- chromosome ol the aphid- 



i- ,1 heterochnuiio-oim- intimately connected with the phenome- 

 non "I ti-rminatiim. 'hr pre-ent im ion ot the- male 

 licnn ( r]l~. I think, leaves no doubt." 



Independently i .f Mi vens, .UK] simultaneously, \Yil-on 

 found ih.it \\herc tlicn- i- Je mono-onie in the- male, it i- 



repre-i nt.-d 1,\ ,1 pair in ii !.; .uid \\hctv a lar^e and -mall 



idiochromosome in the former, tl air of 1 nes in the 



lattrr. In lr d him-elf 



yjiardedly a- to Mich chrom, ilril with -r\ual 



|.h. -110111. n. i. In hi- third -tud\ i much fulK-r 



di-cn--ii>n. .unl it i- tin- trratnu-nt nmrr than an\ other, that ha- 

 .iroii-cd -, iirr.il in 1 in th<- su ll<- mention- as one 



,dtcrn.iti\e th.it nn-n-ly ((iiant hat i\ i- dilVerencc in amount of 

 ill.- < liroin.itin may 1 >e the determinir. >r. lull he crilici-c- 



ihi- for the reason thai in ' iiochromo-..me- are o| 



eipial -i/e in hoth \\hilr .1 .id.ttioii- are 



ki'o\\n I ! \\ern -tich .1 .otiditioii and the one \\here I!ICM- . lc- 

 ments are di--imilar in -i/e in tin I he maintain- 



(In- alternative \ ic\\ . th.u the all - ha\e <|iialit.iti\e dif- 



1,1, n. i - ih.it an \\ilh Mendcli.m doinin.i' 



and with selective fertilization. ral interpretation . . . 



mii-t include tin- .1 umpiion th.u ih- two kind- ot , 



(piv-umalil\ in ,i| i]'io\im.iicl\ cijiial numl'er- thai contain re- 



-|Kcii\cl\ the mali- and the female-determinant, and that the 

 former are fertilized only 1>\ -pern. i that lack tin- hei. 



tropic chnuiio-i .111. the n: -ninant i and 



. . . Su.-h a selective leiiili/.uion i- then-fore a sine '/mi unit 

 of Hi. .1 umptioii thai the h> ropic chroino-onie i- a -pe. itic 



determinant." In tin- ar-nment \\'il-oii makes Use ot 

 ( tie's 1903 hypothesis that sex follows the rule of Mendelian 



ilion and dominance. To thi- \ie\\ he adhen- al-o in 



hi- fourth and tilth studies i- Hut in hi- la-t paju-r 



loo,,, i he oppo-e- tin- Mi lidelian interpretation, U-. ause - I- - 



the fertili/ation i- impn.liaMe. He ! - anotlu-r objection 



the case of tin- bee; luie ih. 'ter two maturation di\i-ions 



