The differentiating mark is only present in one of the parents
and wanting in the other. While all other units are paired in the
hybrid, this one is not. It meets with no mate, and must therefore
remain unpaired. The hybrid of two such elementary species is in some
way incomplete and unnatural. In the ordinary course of things all
individuals derive [254] their qualities from both parents; for each
single mark they possess at least two units. Practically but not
absolutely equal, these two opponents always work together and give to
the offspring a likeness to both parents. No unpaired qualities occur in
normal offspring; these constitute the essential features of the hybrids
of species and are at the same time the cause of their wide deviations
from the ordinary rules.
Turning now to the varieties, we likewise need discuss their
differentiating marks only. In the negative types, these consist of the
apparent loss of some quality which was active in the species. But it
was pointed out in our last lecture that such a change is an apparent
loss. On a closer inquiry we are led to the assumption of a latent or
dormant state. The presumably lost characters have not absolutely, or at
least not permanently disappeared. They show their presence by some
slight indication of the quality they represent, or by occasional
reversions.
Pages:
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256