It
should, however, be observed that in the last experiment (Table 4/31),
the crossed plants competed with plants of the third self-fertilised
generation; whilst in the present case, plants derived from a cross with
a fresh stock competed with self-fertilised plants of the first
generation.
The crossed plants in the present case, as in the last, were more
fertile than the self-fertilised, both lots being left uncovered in the
greenhouse. The thirty crossed plants produced 103 seed-bearing
flowers-heads, as well as some heads which yielded no seeds; whereas the
twenty-nine self-fertilised plants produced only 81 seed-bearing heads;
therefore thirty such plants would have produced 83.7 heads. We thus get
the ratio of 100 to 81, for the number of seed-bearing flower-heads
produced by the crossed and self-fertilised plants. Moreover, a number
of seed-bearing heads from the crossed plants, compared with the same
number from the self-fertilised, yielded seeds by weight, in the ratio
of 100 to 92. Combining these two elements, namely, the number of
seed-bearing heads and the weight of seeds in each head, the
productiveness of the crossed to the self-fertilised plants was as 100
to 75.
The crossed and self-fertilised seeds, which remained after the above
pairs had been planted, (some in a state of germination and some not
so), were sown early in the year out of doors in two rows.
Pages:
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172