234 ILLEGITIMATE OFFSPRING OF CHAP. V. 



these seeds 20 long-styled great-great-grandchildren 

 were raised, which were likewise kept in the greenhouse. 

 Thirty of their flowers were fertilised with their own 

 pollen and yielded 17 capsules, containing on an aver- 

 age no less than 32 mostly fine seeds. It appears, 

 therefore, that the fertility of these plants of the fourth 

 illegitimate generation, as long as they were kept 

 under highly favourable conditions, had not decreased, 

 but had rather increased. The result, however, was 

 widely different when they were planted out of doors 

 in good soil, where other cowslips grew vigorously and 

 were completely fertile; for these illegitimate plants 

 now became much dwarfed in stature and extremely 

 sterile, notwithstanding that they were exposed to the 

 visits of insects, and must have been legitimately fer- 

 tilised by the surrounding legitimate plants. A whole 

 row of these plants of the fourth illegitimate genera- 

 tion, thus freely exposed and legitimately fertilised, pro- 

 duced only 3 capsules, containing on an average only 

 17 seeds. During the ensuing winter almost all these 

 plants died, and the few survivors were miserably un- 

 healthy, whilst the surrounding legitimate plants were 

 not in the least injured. 



The seeds from the great-great-grandchildren were 

 sown, and 8 long-styled and 2 short-styled plants of 

 the fifth illegitimate generation raised. These whilst 

 still in the greenhouse produced smaller leaves and 

 shorter flower-stalks than some legitimate plants with 

 which they grew in competition; but it should be ob- 

 served that the latter were the product of a cross with 

 a fresh stock, a circumstance which by itself would 

 have added much to their vigour.* When these ille- 

 gitimate plants were transferred to fairly good soil 



* For full details of this experiment, see my ' Effects of Cross and 

 Self-fertilisation,' 1876, p. 220. 



