238 ILLEGITIMATE OFFSPRING OF CHAP. V. 



diate state between the long-styled and short-styled form, 

 but inclining towards the short-styled; and this accounts 

 for the low average of seeds which it produced when spon- 

 taneously self -fertilised. 



The foregoing five plants thus differ much from one an- 

 other in the nature of their fertility. In two individuals 

 a great difference in the length of the pistil during two 

 succeeding years made no difference in the number of seeds 

 produced. As all five plants possessed the male organs of 

 the short-styled form in a perfect state, and the female 

 organs of the long-styled form in a more or less complete 

 state, they spontaneously produced a surprising number 

 of capsules, which generally contained a large average of 

 remarkably fine seeds. With ordinary cowslips, legiti- 

 mately fertilised, I once obtained from plants cultivated 

 in the greenhouse the high average, from seven capsules, 

 of 58.7 seeds, with a maximum in one capsule of 87 seeds ; 

 but from plants grown out of doors I never obtained a 

 higher average than 41 seeds. Now two of the equal-styled 

 plants, grown out of doors and spontaneously self-ferti- 

 lised, gave averages of 44 and 45 seeds; but this high fer- 

 tility may perhaps be in part attributed to the stigma re- 

 ceiving pollen from the surrounding anthers at exactly the 

 right period. Two of these plants, fertilised with pollen 

 from a short-styled cowslip (and this in fact is a legitimate 

 union), gave a lower average than when self -fertilised. 

 On the other hand, another plant, when similarly fertilised 

 by a cowslip, yielded the unusually high average of 53 

 seeds, with a maximum of 67. Lastly, as we have just seen, 

 one of these plants was in an almost exactly intermediate 

 condition in its female organs between the long- and short- 

 styled forms, and consequently, when self-fertilised, 

 yielded a lower average of seed. If we add together all 

 the experiments which I made on the equal-styled plants, 

 41 spontaneously self-fertilised capsules (insects having 

 been excluded) gave an average of 34 seeds, which is ex- 

 actly the same number as the parent-plant yielded in Edin- 

 burgh. Thirty-four flowers, fertilised with pollen from 

 the short-styled cowslip (and this is an analogous union), 

 produced 17 capsules, containing an average of 33.8 seeds. 

 It is a rather singular circumstance, for which I cannot 

 account, that 20 flowers, artificially fertilised on one occa- 



