1915] BARTLETT—MASS MUTATION 435 
they may be called for convenience, exhibit mass mutability super- 
posed upon their ordinary behavior in heredity. In order to present 
the data in regard to this point it will be necessary to anticipate 
somewhat the publication of the next article of this series. 
Among the mutations of O. pratincola which have been obtained 
both from Lexington E and from the strains showing only ordinary 
lexi7gior? LB Fete 7 
<—— Oo a77 
hes 3.—Progeny of Lexington E-5, pan 7 (part of culture 3; the remainder is 
in fig. 2; see table II); the pan contains 26 plants, which were classified at 
ate as follow 
- =: - < 
Row ae r | 2 | 3 | 4 | 5 
meer 
| | 
Hawes formosa| setacea | ens (no. r0%} setacea | setacea | 
see 0) 
CS Taos | typica | albicans! setacea | s setacea | typica | 
Se | typica | setacea setacea | albicans| — } 
rE ae | typica setacea | typica | typica 
} | 
| { 
§. wedges setacea | setacea | setacea | setacea petro | setacea (no. 88; 
| see fig. 6) 
| i 
