ARE PARTICULAR CHROMOSOMES SEX DETERMINANTS? II 



noi prove thi- point. But however the-c differences arise they 

 arc clearly pre-ent early in the growth period, which i- -trong 

 c\ id cm c that they cannot he pn >duccd l>y any Mining of allosomes 

 in I'erlili/ation. And it i- (|tiite pn ihle.a- Beard ha- iva-oned. 

 lli.it a di-tinctioii "I" male and female eggs may l>e a general 

 phenomenon, though not u-uall\ .1 ociated with dinuxaly. 



4. In partln-n"ueiif- : - rily determined without 

 fei i ili/ation ; from Mich eggs of I\ot.it< >ri.i. aphid-, l'h\ llo\er,m- 

 .ind d.iphnid- limh mali-- .md female- dexelnp. SiiU'e there i- 

 110 fertili/.ition tin- daughter indi\ idnal- -hoiild ha\e the -ame 

 chromosome compl. he parent, -Imuld all 1 >e it-male-, were 



determined 1>\ particular dimmo-oiii. 1 Uc there -hoiild 



l>i .intii i]i.iied -eparatioiis i.f particular chroin, .-< une- in definite 

 m. inner-, \\hich \\mild -eem to ini]p|\ nio-t coni]iK-\ mechanit .d 



i no \ ci in-lit-; asyel \\- kno\\ nothing definite of such mo> emem-. 



5. In hermaphroditic -; ri-eto a l>i-e\ual 

 iiuli\ iilu.il, ne\t-r to ,i uni-e\ual. \\Vn- t!n-r- - \ determination 

 l>\ |>.u -iii ul. u coinliination- of allo-..me- in the lertili/cd egg, \\ e 

 \\ould nei c--.ii il\ i -\p. i-ioii.il uni-e\ual indixidual- to re- 

 Mill, [n Sagitta Stevens 1005 found an allosome in the sperma- 



1'iit neither in odgenesis nor in the tir-t cleavage; and 



>he. ' uliii ivho described one in the plant S .'/</, 



|ioint- out t hat -in h .in element can ha\- no -c \ii.il \ a hie in 1 1 



hermaphrodit 



A- \\'il-oii and other- ha\ e n-ali/ed. to regard ]i.irtii nl.ir allo- 

 SOmi e\-deiei ininant- logically n. elective 



li i i ili/ation. I mil a .e fert ili/at ion ha- ln-en 



demoii-l rated. l)o\\,-\,-r. the di-cu ion mi tlli- point had lietler 

 In- t.lMed. 



7. M..i-an ha- ur-^ed th.it it m.i\ In- tin- ma rather than the 



<iualit\ oi the chromosome substance that ma\ be sex-determina- 

 tive, pio\id,-d that -uch -uli-tance i- d-ti nninativc at .ill. Il i- 

 the general rule in in-ect- that the male ha- less chromosome 



Mili-iance than the lem.ile. in ha\ : -in.Je mono-, ,nie, or a 



-mall and l.ir^e idiochromosome in the place of tuol.ir^e one-. 

 It mi;Jit then he .tinned that -uch allo-. .nu--, 1 >\ tin- diflen in e 

 in ma \\hich the\ occasion, e-taMi-h the proM>ecti\'e sex \alue. 



! lt is net actually |n\-i-n that i .111. il n.itun-. 



