452 BOTANICAL GAZETTE [DECEMBER 
female gametes. So far, there is no evidence that the pollen of 
any of the characteristic mutations differs from that of f. typica. 
Fic. 14.—Mut. formosaXf. typica (Lexington 
E-5-206 X E-5-229, one of the F; progeny): this 
in table VI; the progenies resulting from self- 
pollination of the parent plants are recorded in 
tables III and VI. 
It follows that mass 
mutation in O. pratin- 
cola must be due to the 
wholesale modification 
of female gametes. The 
relations have not been 
worked out in the case of 
O. Reynoldsii, which also 
shows mass mutability. 
There can be no 
doubt that mass muta- 
tion is not Mendelian 
segregation, although 
the two phenomena 
have points of resem- 
blance. HERIBERT- 
Nitsson’s hypothesis to 
account for the muta- 
bility of O. Lamarckiana 
depends upon the segre- 
gation of plural factors 
for the same character, 
and involves such com- 
plications as the elimina- 
tion of all zygotes which ~ 
are homozygous with re- 
gard to the presence of 
any of the numerous 
plural factors. Needless 
to say, he has also relied 
upon the doctrine of the 
equivalence of male and 
female gametes. His 
last paper bears evidence that his faith in the equivalence of 
gametes is beginning to waver, although he has formerly trusted so 
