MATROCLINIC INHERITANCE 
127 
It appears at present that mass mutation in Oe. Reynoldsii differs 
considerably from the similar process in Oe. pratincola, the chief dif- 
ference being that in the former species the characteristic mutations 
are produced only by certain individuals of f. typica in which there is 
great seed sterility, whereas in the latter species any individual of 
f. typica belonging to the mass mutant strain may give rise to the 
characteristic mutations, the mutable individuals differing widely 
among themselves in mutability and seed sterility. The process is 
alike in both species in that the characteristic mutations occur only 
in strains some members of which are excessively mutable (i. e., 
mass-mutant) and in that the characteristic mutations in both cases 
show matroclinic inheritance. 
Before turning to the evidence in regard to matroclinic inheritance 
there is a further feature of seed abortion to which attention should 
be called. The germination data in Table I show clearly that muta- 
tions arising from highly infertile mass-mutant f. typica are not them- 
selves excessively infertile. The degree of seed abortion is not nearly 
as great in the mutations as in the parent plant that produced them. 
Seeds of mass-mutant f. typica have given germinations varying from 
2.3 to 5.1 percent. In striking contrast to this low viability, seeds 
of mut. semialta have given germinations of 88.7 percent and 62.0 
percent ; seeds of mut. rigida, 72 .0 percent. The germinations recorded 
for mut. hilonga are much lower than the true value, because only 
green plants that survived were counted. This mutation has the 
curious characteristic of giving rise to progenies consisting of a mixture 
of green and yellow plants. The latter lack the capacity for chloro- 
phyll production, and die shortly after the cotyledons unfold. The 
relative numbers of green and yellow plants have not yet been deter- 
mined. Leaving yellow plants out of consideration, mut. hilonga has 
given progenies numbering 34.6 percent, 24.0 percent, and 25.9 percent 
of the number of seeds sown — well in excess of the viability of mass- 
mutant f. typica. Complete records have been kept for only one 
progeny of mut. debilis. This form is a weak dwarf, of which the 
seeds are much less viable than those of the other mutations. Only 
7.5 percent of germinations were obtained. It must be remembered, 
however, that mut. debilis, the most sterile of the mutations, gives 
rise to mut. hilonga, a form showing a distinct increase in fertility over 
its parent. We can not doubt that in the case of the mutations seed 
sterility is in a large measure inversely proportional to the vegetative 
vigor of the parent plant. 
