426 



THE AMEBIC AX X ATE BALIS'!' [Vol. XLYI 



It is to be regretted that the terms mutant and muta- 

 tion are being used so variously by different workers in 

 the fields of genetics. "Mutations" have been described 

 which are obviously from heterozygous parentage, in 

 some cases small differences, as of color or measurement, 

 in other cases very large differences. In contrast to 

 these have been described "mutations" from possible 

 homozygous parentage. Germinal variation due to the 

 mixing of different germ-plasms, and consequently from 

 heterozygous material, is a common phenomenon and 

 easily defined. Germinal variation in homozygous ma- 

 terial presents an equally clear concept. The two types 

 of variation should be sharply distinguished for one of 

 the most important fields of genetical research is the 

 study of possible germinal variations in homozygous 

 stock and the conditions under which they may occur. 



In our understanding of germinal variations (muta- 

 tions) as distinguished from somatic variations (fluctua- 

 tions) a great advance has been made towards a clear ap- 

 preciation of the problems involved. The problems cen- 

 ter in the study of germinal variations which are of two 

 types since they may be due to the mingling of germ 

 plasms (amphimixis), or to environmental influences. 

 Amphimixis is of course responsible for heterozygous 

 conditions now better understood as a result of Mende- 

 lian studies. Eelatively little is known, however, of the 

 conceivable effects of environment as a source of germi- 

 nal variation. It may be doubted whether the specific 

 terms "mutation" and its alternative "fluctuation," as 

 commonly used, are well chosen since the concepts are so 

 clearly expressed by the designations germinal and 



It is clear that De Vries regarded the "mutants" of 

 Lamarcl'iana as variants from a type representative of a 

 wild species and as nearly homozygous as most well- 

 defined species. That the Lamarchiana with which De 

 Vries worked was strongly heterozygous, in fact a hybrid 

 of biennis and grandiflora, is the hypothesis for which I 

 am trying to present as much evidence as possible. By 



