On the other hand, it disappeared from amongst the
crossed plants in the later generations; and this was probably due to
the continued intercrossing of the several plants. From the tallness of
this variety, the self-fertilised plants exceeded the crossed plants in
height in all the generations from the fifth to the seventh inclusive;
and no doubt would have done so in the later generations, had they been
grown in competition with one another. In the fifth generation the
crossed plants were in height to the self-fertilised, as 100 to 126; in
the sixth, as 100 to 147; and in the seventh generation, as 100 to 137.
This excess of height may be attributed not only to this variety
naturally growing taller than the other plants, but to its possessing a
peculiar constitution, so that it did not suffer from continued
self-fertilisation.
This variety presents a strikingly analogous case to that of the plant
called the Hero, which appeared in the sixth self-fertilised generation
of Ipomoea. If the seeds produced by Hero had been as greatly in excess
of those produced by the other plants, as was the case with Mimulus, and
if all the seeds had been mingled together, the offspring of Hero would
have increased to the entire exclusion of the ordinary plants in the
later self-fertilised generations, and from naturally growing taller
would have exceeded the crossed plants in height in each succeeding
generation.
Pages:
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134