150 HETEKOSTYLED TRIMOEPHIC PLANTS. CHAP. IV. 



three forms. Thus the long-styled form has to be fer- 

 tilised \i ith pollen from its own two kinds of anthers, 

 from the two in the mid-styled, and from the two in 

 the short-styled form. The same process has to be 

 repeated with the mid-styled and short-styled forms. 

 It might have been thought sufficient to have tried on 

 each stigma the green pollen, for instance, from either 

 the mid- or short-styled longest stamens, and not 

 from both ; but the result proves that this would 

 have been insufficient, and that it was necessary to 

 try all six kinds of pollen on each stigma. As in 

 fertilising flowers there will always be some failures, 

 it would have been advisable to have repeated each of 

 the eighteen unions a score of times; but the labour 

 would have been too great; as it was, I made 223 

 unions, i.e. on an average I fertilised above a dozen 

 flowers in the eighteen different methods. Each flower 

 was castrated ; the adjoining buds had to be removed, 

 so that the flowers might be safely marked with 

 thread, wool, &c. ; and after each fertilisation the stigma 

 was examined with a lens to see that there was suffi- 

 cient pollen on it. Plants of all three forms were 

 protected during two years by large nets on a frame- 

 work ; two plants were used during one or both years, 

 in order to avoid any individual peculiarity in a par- 

 ticular plant. As soon as the flowers had withered, 

 the nets were removed ; and in the autumn the cap- 

 sules were daily inspected and gathered, the ripe 

 seeds being counted under the microscope. I have 

 given these details that confidence may be placed 

 in the following tables, and as some excuse for two 

 blunders which, I believe, were made. These blunders 

 are referred to, with their probable cause, in two 

 foot-notes to the tables. The erroneous numbers, how- 

 ever, are entered in the tables, that it may not be sup- 



