168 SYMBIOGENESIS 



view of the metabolic connections, again indicates that in the 

 last analysis we are here dealing with qualitative processes of 

 an economic order (distribution !) with which we must assume 

 the fertilisation process to be largely concerned. 



As was pointed out by Dr. Doncaster in Nature (16/4/14) : 

 " Cytological Aspects of Heredity would seem to afford strong 

 support to the view that the chromosomes play a very 

 important part in the transmission of Mendelian characters 

 (although the part played by the cytoplasm must also be taken 

 into account)." With regard to sex-determination, with which 

 Dr. Doncaster is particularly concerned, he says that difficulties 

 arise in connection with the fact that this has been shown in 

 certain cases to be modifiable by environmental conditions, and 

 e: it therefore appears probable that the sex chromosome is 

 associated with a particular type of cell-metabolism, which in 

 turn is responsible for sex-determination." 



It is clear that the metabolism of the sex chromosome is 

 largely determined by the general metabolism of the species, 

 and this in turn by the bio-economic functions of the species. 

 Hence we see again that the generic metabolism of the 

 organism is a very responsible determinant of (chromosome) 

 value and chromosome behaviour, and hence also of the evolu- 

 tion of sex generally. The connection between Mendelian 

 phenomena and bio-economic factors thus also becomes once 

 more emphatic. 



Dr. Walker is willing with some modifications to concede 

 the claim that the sex "character" behaves as a Mendelian 

 factor. But we see now that it is more profoundly true 

 that Mendelian characters behave like sex characters, 

 i.e., they either make or mar the zygote according 

 to the bio-economic adequacy of the union. Alternative 

 " characters," including sex, either stand in genuine reciprocal 

 relation to each other and thus enrich the species by their 

 union, or under retrograde (metabolic) compatibilities they 

 produce unions which end with an impoverishment of the 



