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7 ///•; - 1 Mh h'ICA X .V, 1 TURALIST [Vol. LI 



liefore the seuTOi-'atioii of pericarp color among- tliem can 

 he seen, for it is exliihited only in the beed coats. Tlie 

 conclusions follow: (1) The egg and all its determinative 

 content is produced under the double influence of the 

 sperm and egg chromatin contributions which united to 

 form the producing zygote. (2) Hybridization experi- 

 ments with egg characters, to be critical, must ])e carried 

 as far the V, generation. {.'3) In all experiments which 

 I liave seen reported, in which this condition ol)tained, the 

 influence of the s])erm on the character^; in question has 

 been observed. 



Loeb's evidence, however, introduces also crosses be- 

 tween Strongyloccnfrofus purpurafus and S. fraiicis- 

 rauus, and the statement is made that the develojmient of 

 the hybrid up to the formation of the skeleton resembles 

 exclusively the development of the mother's species. But 

 Loeb also finds that tlie cross-barring in the spicules of 

 purpiiinfii^ b('li;i\('^ a< a dominant character in reciprocal 

 cr(f.^<< llf ;i--iL;ii- tliis character to a factor, which he 

 imauinc> to be :\ !'( riiient or enzvme. This statement fol- 

 h.w.: ••Sip.r iIh- pu,v pHrpuratus ha^ two determiner^ 

 \nv tl,.. d.-xdnp„M-nt of tlu' .To^. b;,,-. aiid l!,<- l,>brid^ 



\i(les here not only evidence thai ;i\-()\ve(l cliromosome 

 cliaracters do affect tlie rate of ih-xelo] mieiit, but even 

 furnishes an enzymatic mechanism b\ which they may do 

 it. x\nd yet soon after tlie above (|U(»tation, we read: 



Tlie whole (■!\>v of tiic -upporters of any theory which 

 \ irw- the .'x-to)";;!-!!! drt ci-miiiative rests on either their 

 iTl'iisil to -o bnrk iiuniire the source of this cyto- 

 ph'isiii. or on tli( ii- ivfu.sil to -ive due emphasis to the 

 source. e\-en tlioug'ii they recognize it. ('onklin recognizes 



