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 possi1)le 

 only to a very limited extent or not at all. In other po- 

 sitions two groups of dissimilar hut 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; 



