82 BOTANICAL GAZETTE [january 





and the various mutants are plants which result when one or more of these 

 groups are in a homozygous recessive condition. This might be represented 

 graphically thus: 0. Lamarckiana^ Aa Aa Aa aa; Bb Bbbbbb; Cc Cc cc cc, 

 etc., where in every group at least one of the factors would be present in the 

 positive condition. A mutant = aa aa aa aa; Bb Bb bb bb; Cc Cc cc cc, etc., 

 where in at least one of the groups none of the factors are present in the positive 

 condition. This interpretation is thought to explain the occurrence of differ- 

 ent ratios of mutation, for if there were 4 such independent multiple factors 

 for the Lamarckiana character, a given mutant dependent upon the absence 



in the following percentage : 1.2 per 

 cent when all of the 4 factors are heterozygous 53.7 per cent when only 3 of the 

 4 factors are heterozygous; n. 1 per cent when only 2 of the 4 factors are 

 heterozygous; 33.3 per cent when only 1 of the 4 factors is heterozygous. 



At several points in his paper the author points out that since different 

 strains of O. Lamarckiana yield different series of mutants it cannot be an 

 elementary species, as DeVries claims, but must be a group of elementary 

 species, the free intercrossing of which makes 1 



occur 



ordinary 



The assumption of extensive 



link 



mission of hereditary characters through the sperms differing from those pos- 

 sessed by the eggs of the same individual), and the assumption that one sort 

 of sperm may hinder the activities of another sort of sperm, are not in strict 



Mendelian 



Oenothera genetics. — Ben C. Helmick 



Mutation in Matthiola annua, a "Mendelizing" species. — In a preliminary 

 paper under the foregoing title Frost 2 has published certain conclusions in 

 regard to the origin of Mendelian dominants which are sure to arouse no little 

 interest. Until the full account appears it will be impossible to judge of the 

 validity of Frost's interpretation of his discoveries, but the discoveries them- 

 selves are obviously of prime importance, interpret them however we may. 

 According to his own view, he has observed the origin by mutation of 8 differ- 

 ent dominant Mendelian varieties from a single strain of stocks. To show that 

 this would be a discovery of the highest theoretical significance, it is only 

 needful to point out that similar evidence is extremely meager, and in prac- 

 tically every case not as well attested as one might wish. The list of new 

 dominants which have arisen by mutation is practically exhausted when we 

 have mentioned Keeble's giant Primula and Collins' albinistic maize, for 

 the case of Gates' Oenothera rubricalyx is still in dispute. 



Frost states that the individual mutations of his Matthiola cultures 

 obviously are not extracted recessives, but heterozygous dominants; that they 

 seem to be due to definite changes in the germ plasm distinct from the recombi- 



ard B., Mutation in Matthiola 



Amer 



