142 
CARL D. LA RUE AND H. H. BARTLETT 
had a lower average position in the inflorescence, for the lower cap- 
sules, if normally developed, are usually longer than those higher up. 
Notwithstanding the difference in material, it is instructive to 
observe the close agreement between the two sets of measurements. 
The difference between the modal lengths for f. typica and mut. semi- 
alta in 191 5 (Maryland) was just 12 mm., the same as the average 
difference between the typica series of cultures and the semialta series 
in 1916 (Michigan). 
The capsule measurements give thoroughly satisfactory evidence 
of matroclinic inheritance. The data for the semialta series of cultures 
are particularly convincing. The modal lengths are the same for 
pure semialta, semialta X t'^^pica, and semialta X bilonga, being 25 
mm. in each case. The ratio of the capsule lengths of the three pollen 
parents is 2:3:4, but the self-pollinated mut. semialta is just like the 
two crosses. Turning to the slightly less consistent data for the 
typica series, the evidence is hardly less satisfactory. In the cross 
typica X dehilis the capsule length is actually slightly higher than 
in pure f. typica, in spite of the shorter capsule of the pollen parent. 
In the cross typica X bilonga the length is slightly greater than in self- 
pollinated f. typica, but that the difference is not significant is certain 
from the fact that the cross typica X semialta has capsules just as 
long. In the one case the pollen parent has a longer, in the other case 
a shorter, capsule than the pistillate parent, but the crosses are iden- 
tical. The results of the capsule measurements, taken all in all, prove 
that matroclinic inheritance is the rule in the mutation crosses under 
consideration, and leads us to suspect that there may be such a thing 
as increased vigor due to cross-pollination, independently of factorial 
recombinations such as those that occur in Mendelian inheritance. 
In the case of the very interesting dimorphic culture resulting 
from the cross debilis X bilonga, it is especially unfortunate that 
capsule measurements were not obtained, because the two forms differ 
so much from one another. That measurements would have fully 
substantiated the conclusions already drawn in regard to this cross is 
certain from the few precocious plants that matured before frost. 
Figure 2 shows typical plants of the cross semialta X bilonga and 
its reciprocal. Of the latter there were too few plants that matured 
to make a series of measurements worth while. The fact of matro- 
clinic inheritance is obvious from the photograph, however, for in 
semialta X bilonga the capsules are only half as long as in bilonga 
