AUTHOR S ABSTRACT OF THIS PAPER ISSUEK 

 BY THE BIIiLIOGRAPHIC SERVICE, MAY 1 



EVIDENCE THAT GERM CELLS ARE SUBJECT TO 

 SELECTION ON THE BASIS OF THEIR GENETIC 

 POTENTIALITIES 



C. H. DANFORTH 



Department of Anatomy, Washington University School of Medicine 



INTRODUCTION 



A great deal of evidence goes to show that individual dif- 

 ferences among adult animals are commonly due to differences 

 in the germ cells from which the animals have developed. In 

 other words, peculiarities in the adult are, in general, indications 

 of peculiarities in the germplasm. It would seem to follow as 

 an obvious corollary of this that the germ cells of a species must 

 be of almost as many classes as are the adult individuals. This 

 being the case, it is perhaps not unreasonable to expect that 

 germ cells should differ more or less widely in their responses 

 to varying conditions and in their ability to function in the 

 production of zygotes. If such an assumption is shown to be 

 justified, it might be invoked to explain several obscure evolu- 

 tionary tendencies, as well as certain constant departures from 

 normal Mendelian expectations. 



As a first step in determining whether or not germ cells carry- 

 ing factors for a given unit character differ in their physiological 

 responses from germ cells carrying factors for an allelomorph 

 of that character, it seems desirable to work with the sperm 

 or eggs of a heterozygous animal in which th6 normal proportion 

 of each class of germ cells produced has already been determined. 

 With such an animal all the gejm cells are presumably subjected 

 to the same influences, except as those influenced are varied by 

 the experimenter, and consequently a much better control is 

 possible than could be had by comparing results from different 

 homozygous individuals. 



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