MUTATION IN MATTHIOLA ANNUA, A MENDELIZING SPECIES 38 1 
more; the plants are small and slender, and under unfavorable con- 
ditions may be extremely dwarfed. 
The narrow-leaved type is characterized by rather rigid narrow 
leaves, flat or concave upward, ascending rather than horizontal; the 
sepals and petals are conspicuously narrow. The narrow-dark-leaved 
type (fig. i) is in some respects more like Snowfiake; its leaves tend to 
be small, very dark green, and smoothly convex upward, while the 
sepals are probably normal. Two variant parents, grown before this 
last type was recognized, have given it among their progeny; one of 
■< ' 
The Smooth-leaved Type 
Fig, 2. Matthiola plants at Riverside, California, in 1913-14. Progeny of a 
Smooth-leaved parent. Types, from left to right: Smooth-leaved, Smooth-leaved, 
Snowflake. Note the lateness of the Smooth-leaved plants, and the punctate ap- 
pearance of some of the leaves (due to small dead spots.) 
these, however, apparently gave four to six other definite types, in- 
cluding Snowflake as usual. 
The slender type, under favorable conditions, is much like Snow- 
flake, but with somewhat lengthened internodes, petioles, and pedicels. 
Under some unfavorable conditions it may be much dwarfed, although 
it seems to endure high temperatures better than Snowflake. Two 
grades of this type have been found; the extreme form, in one small 
test, gave the larger proportion of slender progeny, but still only nine 
plants out of sixteen. In this last case the plants were all doubles, 
and elsewhere there is, apparently, linkage of a specially puzzling sort 
with the single-double factor-pair. 
