292 



77/ /•; . 1 .1/ /•; /,■ n A \ x . i tura list 



[Vol. LI 



the maximum of Gm])lia>l>. and the I'orc.uoino- criticism 

 has been intended to indicate that it- ^njtport of the c}i;o- 



mized as to be non-existent. However, Shull does place 

 mucli empliasis on some carefully collected evidence of 

 his own. This does not, 1 believe, support his theory to 

 any g'reater extent than his quoted cases. 



The evidence is briefly as follow^s: Shull crossed tw^o 

 lines of rotifers which differed in two e^2;-g characters- 

 time of hatchin<>- of sexual eo'<>-s, and the proportions of 

 M'xual whicli actually hatched. The e-ji's of line ''A" 

 liatclu'(j on tlic ax'ciaiic In 1 -I weeks, about 50 i)er cent, 

 cmci-.-inu'. I/nic •'ir' cu-> took 5-6 weeks to hatch and 

 only 5 pel' ctMit. cnicrucMl. \auq "A" females fertilized 

 1>\- line ''.B" si>erm laid e^iigs which hatched in 1-3 wrecks, 

 51) per cent. emeri>'ini>-. The eg"f>"s thus resembled the 

 mother's line in both respects. Line "B" females fer- 



than tlic father"-. The reciprocal liybrid> are thn> very 

 une(pial. >ay> Slmll. and -Ince in cr<.»in- jiarents wliich 

 differ I.> M. ndelian. .-hi'. .nio-onie detei-niined characters, 

 the re-ultitm- reciprocal h\l.ri.U aiv e.|iiai. the ch.aracters 



the cyt()i)lasni (»f the cu-. 



But it is to be objecded tlial in reaiilx the-e li>l,rid eo-trs 

 of the first generation arc not h\-i»i'id in the>e characters 

 at all. The characters arc eu^' cliaractei-s and as such can 

 be exhibited only when the h\lti-id zyg'ote ])roduces its 

 eg^>, not when tlic liyl)i-id zy-ote is formed. The expres- 

 sion of the (diai'acter i> thn- delayed until the hatchino- of 

 eo-,u> laid l.y tla-e K, /> -ote-. And Shull^ data ^how< 

 this to he the case. 



NoWtlle MMial oceui-ren.'e i- ol.-erVed. vi/.. the recipr.H'al 



hybrids are e<|ual and the contributions to the character 



