No. 609] THE THEORY OF THE GENE 533 



as an important theoretical possibility. But it must not 

 be forgotten that the only characters that we know any- 

 thing about in genetics are under nuclear control with the 

 exception of plastids that can themselves multiply in the 

 cytoplasm. 



There is a special case of inheritance that has been 

 called cytoplasmic that may equally well have a chro- 

 mosomal explanation. Goldschmidt tinds that he can 

 account for certain of his results in gypsy moths by as- 

 cribing certain values to the cytoplasm. Thus he says 

 the two factors for femaleness (FF) are transmitted from 

 the mother to her daughters and the latter transmits 

 again to their daughters, etc. In other words, the factors 

 are carried only in the egg-producing line. Groldsclmiidt 

 concludes that the evidence proves that the ''FF com- 

 plex is inherited ... in the protoplasm of the female." 

 Xow in motlis in wliicli the female is the heterogametic 

 se.v. tlic V cln'oiiio^otiic (or the W cliromosome to use a 

 dinVi-ciit iKMtu'iiclatmc ) t ransmitted only by the female 

 line and should this chroinosome carry the factors in 

 question all the re([uireuients of the experiment would be 

 fulfilled. There is no way of determining from this evi- 

 dence alone whether the case belongs to the phistid type 

 of inheritance, or is {i case of W inheritance, exce])t by 

 finding species in which the rcinah' norninlly hncks the 

 W M>x clironin.oin... ,m- h> ^ouic .•imniM hni^ .-ondition has 

 h>^t it a> in the .V) <-hi'.,in.,M)nic tVmah- tiiat Donca^ler 

 lias found in the moth AhrnMis. 



There i> still another rOle that the ex topla^iii may play 

 in determining the nature of tlu' next event to occur. In 

 PhylloNerans it ha> l)een shown that n whole mvx chromo- 

 some i.s eliminated iVom tile -mall eiiu- and in eon>e(iuence 

 a male re>ult- fi-.Mi! them. The pieMimption here is that 

 the effect i- tlii'.umh the .-MeplaHu determinino- the dis- 

 tribution ot* the eiir..im)^nm(.-. hut it muM W roneeded 

 tlmt th.' -nme ,mvirnm,u'ntui Av.m-v^ thai .-i tfeet the 

 cytopl;i-m mny have hud a Muiultanenu^ ,.|r..-! nn .,!u- of 

 the >ex ('hn)mo>ome<. In the case of eei'tuin -enerie 



