162 HETEEOSTYLED TKIMOEPHIC PLANTS. CHAT. IV. 



is that the mid-styled form differs from both the 

 others in its much higher capacity for fertilisation 

 in various ways. Not only did the twenty -four flowers 

 legitimately fertilised by the stamens of corresponding 

 lengths, all, or all but one, yield capsules rich in 

 seed ; but of the other four illegitimate unions, that 

 by the longest stamens of the short-styled form was 

 highly fertile, though less so than the two legitimate 

 unions, and that by the mid-length stamens of the 

 long-styled form was fertile to a considerable degree ; 

 the remaining two illegitimate unions, namely, with 

 this form's own pollen, were sterile, but in different 

 degrees. So that the mid-styled form, when fertilised 

 in the six different possible methods, evinces five 

 grades of fertility. By comparing compartments III. 

 and VI. in Table 24 we may see that the action of 

 the pollen from the shortest stamens of the long-styled 

 and mid-styled forms is widely different; in the one 

 case above half the fertilised flowers yielded capsules 

 containing a fair number of seeds ; in the other case 

 not one capsule was produced. So, again, the green, 

 large-grained pollen from the longest stamens of 

 the short-styled and mid-styled forms (in compart- 

 ments IV. and V.) is widely different. In both these 

 cases the difference in action is so plain that it cannot 

 be mistaken, but it can be corroborated. If we look 

 to Table 25 to the legitimate action of the shortest 

 stamens of the long- and mid-styled forms on the 

 short-styled form, we again see a similar but slighter 

 difference, the pollen of the shortest stamens of the 

 mid-styled form yielding a smaller average of seed 

 during the two years of 1862 and 1863 than that from 

 the shortest stamens of the long-styled form. Again, 

 if we look to Table 23, to the legitimate action on 

 the long-styled form of the green pollen of the two 



