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THE AMERICAN NATURALIST [Vol. XLV 



ive factors combined with tradition, the latter not only 

 conserving the valuable types but actively stimulating 

 their improvement. But all this has nothing at all to do 

 with the biological notion of heredity. It is of course 

 interesting to see that the idea of "evolution by selec- 

 tion" has won credit in archeology, sociology, etc., but 

 this involves nothing as to genetics, for which "tradi- 

 tion" is irrelevant. 



The very "radical" form of the genotype-conception 

 advocated here may be too "theoretical" to be carried 

 through in all its consequences in cases of practical ex- 

 periments in genetics. In nature and even in the chem- 

 ical factories the chemical compounds are not always to 

 be had in quite pure state. The history of a prepara- 

 tion may sometimes be traced by accompanying impuri- 

 ties. As to the analogy with the genotypes we touch 

 here the question whether the genotypical constitution 

 of a gamete may not be accompanied by some accessorial 

 or accidental "impurities" from the individual organ- 

 ism in which the gamete was developed. 



Here we meet with the cases of "spurious" heredity, 

 e. g., the infections of the gametes or zygotes as may be 

 seen in certain cases of tuberculosis, syphilis, etc. Such 

 and other forms of spurious heredity may have the ap- 

 pearance of "hereditary transmission" or "ancestral 

 influence"; but theoretically they do not interfere at all 

 with the genotype-conception of heredity. In such in- 

 teresting cases as that detected by Correns, viz., the 

 "heredity" of a special form of albinism by "trans- 

 mission" through the plasm of the ovum— the sperm not 

 transmitting this character— we may at the first glance 

 be puzzled. Nevertheless, as Correns himself points out. 

 here we have certainly to do with a pathological state of 

 the plasm or the chromatophores in question, and that 

 may perhaps be the reason for the lack of heredity 

 through the sperm which carries no ( ?) plasm or only a 

 small quantity. The etiology of such abnormalities 

 being as yet quite unknown, it may often be very difficult 

 to distinguish them clearly from "genotypically" de- 



