108 HETEROSTYLBD DIMOEPHIC PLANTS. Chap. III.' 



flowers in the first line was probably accidental, and 

 if so, the difference in the proportion of legitimately 

 and illegitimately fertilised flowers which yield fruit 

 is really greater than that represented by the ratio of 

 100 to 35. The 18 long-styled flowers illegitimately 

 fertilised yielded no seeds, — not even a vestige of one. 

 Two long-styled plants which were placed under a net 

 produced 138 flowers, besides those which were arti- 

 ficially fertilised, and none of these set any fruit; nor 

 did some plants of the. same form which were pro- 

 tected during the next summer. Two other long- 

 styled plants were left uncovered (all the short-styled 

 plants having been previously covered up), and 

 humble-bees, which had their foreheads white with 

 pollen, incessantly visited the flowers, so that their 

 stigmas must have received an abundance of pollen, 

 yet these flowers did not produce a single fruit. We 

 may therefore conclude that the long-styled plants are 

 absolutely barren with their own-form pollen, though 

 brought from a distinct plant. In this respect they 

 differ greatly from the long-styled English plants of 

 P. officinalis, which were found by me to be moderate- 

 ly self -fertile ; but they agree in their behaviour with 

 the German plants of P- officinalis experimented on by 

 Hildebrand. 



Eighteen short-styled flowers legitimately fertilised 

 yielded, as may be seen in Table 30, 15 fruits, each 

 having on an average 2.6 seeds. Four of these fruits 

 contained the highest possible number of seeds, namely 

 4, and four other fruits contained each 3 seeds. The 

 13 illegitimately fertilised short-styled flowers yielded 

 7 fruits, including on an average 1.86 seed; and one 

 of these fruits contained the maximum number of 

 4 seeds. This result is very surprising in contrast 

 with the absolute barrenness of the long-styled flowers. 



