When occurring in the
seeds of the variety they betray themselves as soon as the differential
characters are displayed. Between the thousands of flowering plants of a
white variety the hybrids will instantly catch the eye by their red or
blue corollas. Quite the contrary effect results from the admixture of
hybrids with the seeds of the species itself. Here no difference will
show itself, even in the fullest bloom. The effect of the spontaneous
crosses will pass unobserved. The strain, if pure in the first year,
will seem to be still in the same condition. Or in other terms, the
unavoidable spontaneous crosses will disturb the purity of the variety
in the second year, while they do not seem to interfere at all with the
uniformity of the species. The direct effect of the visits of the
insects is evident in the first case, but passes unobserved in the
latter.
From this it would seem, that spontaneous crosses are hurtful to
varieties, but are innocuous to true species. Certainly this would be
so, were there no selection. But it is easily seen, that through this
operation the effect becomes quite the opposite. For when the fields
[210] are inspected at the time of the fullest display of the varietal
characters, the obvious hybrids will be eliminated, but the hidden ones
will of necessity be spared, as they are concealed among the species by
the similarity of their type.
Pages:
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216