4.
The two illegitimate unions together :
17 : 3 : 2.1.
It follows from this table that 88 per cent of the paired flowers of both forms,
when legitimately fertilised, yielded double berries, nineteen of which
contained on an average 4.4 seeds, with a maximum in one of 8 seeds. Of the
illegitimately fertilised paired flowers only 18 per cent yielded berries, six
of which contained on an average only 2.1 seeds, with a maximum in one of 4
seeds. Thus the two legitimate unions are more fertile than the two
illegitimate, according to the proportion of flowers which yielded berries, in
the ratio of 100 to 20; and according to the average number of contained seeds
as 100 to 47.
Three long-styled and three short-styled plants were protected under separate
nets, and they produced altogether only 8 berries, containing on an average only
1.5 seed. Some additional berries were produced which contained no seeds. The
plants thus treated were therefore excessively sterile, and their slight degree
of fertility may be attributed in part to the action of the many individuals of
Thrips which haunted the flowers. Mr. J. Scott informs me that a single plant
(probably a long-styled one), growing in the Botanic Gardens at Edinburgh, which
no doubt was freely visited by insects, produced plenty of berries, but how many
of them contained seeds was not observed.
Pages:
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183