CHAP.V. HETEROSTYLED DIMORPHIC PLANTS. 233 



and especially by the long endurance of the flowers. 

 For instance, I fertilised many flowers on these plants, 

 and fifteen days afterwards (viz. on March 22nd) I 

 fertilised numerous long-styled and short-styled flowers 

 on common cowslips growing close by. These latter 

 flowers, on April 8th, were withered, whilst most of the 

 illegitimate flowers remained quite fresh for several 

 days subsequently; so that some of these illegitimate 

 plants, after being fertilised, remained in full bloom 

 for above a month. 



"We will now turn to the fertility of the 53 illegiti- 

 mate long-styled grandchildren, descended from the 

 long-styled plant which was first fertilised with its 

 own pollen. The pollen in two of these plants included 

 a multitude of small and shrivelled grains. Never- 

 theless they were not very sterile; for 25 flowers, fer- 

 tilised with their own pollen, produced 15 capsules, 

 containing an average of 16.3 seeds. As already 

 stated, the probable average with legitimate plants 

 for a union of this nature is rather above 20 seeds. 

 These plants were remarkably healthy and vigorous, 

 as long as they were kept under highly favourable 

 conditions in pots in the greenhouse; and such treat- 

 ment greatly increases the fertility of the cowslip. 

 When these same plants were planted during the next 

 year (which, however, was an unfavourable one), out 

 of doors in good soil, 20 self-fertilised flowers produced 

 only 5 capsules, containing extremely few and wretched 

 seeds. 



Four long-styled great-grandchildren were raised 

 from the self-fertilised grandchildren, and were kept 

 under the same highly favourable conditions in the 

 greenhouse; 10 of their flowers were fertilised with 

 own-form pollen and yielded the large proportion of 6 

 capsules, containing on an average 18.7 seeds. From 

 17 



