424 CORRADO GINI 



polymeria and that of polyploidy. 41 It is easy to convince oneself that 

 the hypothesis of polymeria could explain a somewhat less important dim- 

 inution than 50 per cent, from the first to the second generation, but it could 

 not explain, in the case of chance mating, a diminution of heterosis beyond 

 the second generation. Polyploidy is, instead, a fit hypothesis to explain 

 satisfactorily the fact that, from the first to the second generation, the dim- 

 inution of heterosis is less than 50 per cent as well as the progressive diminu- 

 tion, in the case of chance mating, of heterosis in the generations following 

 the second one. 



I think that these considerations deserve the particular attention of 

 eugenists, as it is well known that numerous human characters are deter- 

 mined by multiple factors. Moreover, it is not improbable that the human 

 species is still at present, or was originally, polyploid. 5 



It will be worth while to revert with greater details to this subject. 6 



4 Concerning the correct distinction between these two hypotheses, I may refer to my 

 paper: "Considerazioni sull'eredita mendeliana nelle forme poliploidi," which was sub- 

 mitted to the Second Italian Congress of Genetics and Eugenics, held in Rome from 

 September 30, to October 2, 1929. 



6 Cfr. the paper mentioned in the preceding note. 



6 1 will revert to it in an article entitled: Considerazioni sul Poliploidismo, written in 

 collaboration with Dr. Castellano, to be published shortly in "Genus," the Journal of the 

 Italian Committee for the study of Population Problems. 



