1907] Brainerd,— Mendel's Law of Dominance in Viola — 213 
fig. 1, in which the purple capsules and brown seeds are shaded, and 
the green capsules and buff seeds are left white. 
a .B 
V. papilionacea 
2.—A.b? 3.—a.B? 4.—a.b! 
Fig. 1.—Capsules and Seeds of Viola hirsutula X papilionacea, and ot its 
Parents and Offspring. 
In 1907 offspring were obtained of six different plants of the eleven 
raised in 1906. In order to interpret the results, the reader who is not 
familiar with the laws of Mendel, will be helped by a brief preliminary 
discussion of the real nature of the four forms of F, that appear as the 
product of the first sowing. As a matter of fact there are five other 
forms, that masquerade under one or another of the first three forms 
shown above. We are not sure, among these, in a plant with purple 
capsules, but that there is also a latent tendency to produce green 
capsules, kept in check in this individual plant by the dominance of 
the purple tendency, but able to assert itself in some of the offspring 
That is, we do not know whether the A is pure A or Aa. Simi- 
larly we are not sure in a plant that bears brown seeds but that there 
is also a latent tendency to bear buff seeds, repressed in this individ- 
ual plant by the stronger tendency to bear brown seeds, but able to 
