648 Vehicles of the Hereditary Characters. 
riod in the development of the organism and, in part, 
escape into the protoplasm, there to exercise their func- 
tions. Diametrically opposite to this is the latent con- 
dition, for in it this kind of multiplication is possible 
only to a very limited extent or not at all. In other po- 
sitions two groups of dissimilar but homologous pangenes 
have a mutual effect upon one another which varies ac- 
cording as the one or the other obtains the mastery. This 
is seen in the case of the vicariating characters of the 
half races and eversporting varieties. Here the two ele- 
ments are affected by external conditions in the same way 
but in vastly different degrees, the phylogenetically older 
one being scarcely at all susceptible, while the younger 
one is highly susceptible. If the latter retires into a 
latent state, as in the case of half races, the degree of their 
manifestation, that is of the migration of the material 
particles, from the nuclei into the protoplasm, is a limited 
one. If, however, they are in the semi-active condition, 
as in the case of the eversporting varieties, the result is 
the extraordinary variability which characterizes these 
races. 
The nature of the difference between uni-sexual and 
Mendelian crosses is now obvious without further dis- 
cussion. If each element finds its partner during the 
formation of the sexual cells of a hybrid, exchange takes 
place as in ordinary fertilization, and the Mendelian 
crosses become merely a special case of this. But if one 
or two or several elements do not find partners, the nor- 
mal process will obviously be disturbed, since the two 
idioplasms do not fit one another exactly. And on the 
degree of this disturbance, that is to say on the number 
of differentiating elements, depend obviously in the first 
place the fertility of the cross, that is to say the capacity 
