No. 579] 



MUTATION EN MASSE 



135 



The two progenies from mut. debilis parents, contain- 

 ing 85 and 43 plants, respectively, were all mut. debilis 

 like the parents, except that each progeny contained one 

 individual of mut. bilonga. Before discussing the latter 

 mutation it may be well to capitulate. 



1. The individuals of f. typica are of two kinds, (a) 

 those which do not throw dwarfs, and (b) those which 

 throw from 60 per cent, to 80 per cent, of dwarfs. 



2. The dwarfs are of two kinds, one of which, mut. 

 semialta, is intermediate between f. typica and the ex- 

 treme dwarf, mut. debilis. 



3. Mut. semialta reproduces itself in the greater part 

 of its progeny, but throws a small number (seemingly 

 about 7 per cent.) of mut. debilis. 



4. Mut. debilis does not throw either f. typica or f. 

 semialta. It comes true, except for the fact that it rarely 

 throws mut. bilonga. 



Mut. bilonga is by far the most interesting of the vari- 

 ants of (Enothera Reynoldsii. It has occurred once as a 



