Chap. V. HETBEOSTYLED DIMOEPHIC PLANTS. 235 



were excluded ; and he explains this fact by showing, first, that 

 the anthers and stigma are in close apposition, and that the 

 stamens in length, position and size of their pollen-grains 

 resemble those of the short-styled form, whilst the pistil re- 

 sembles that of the long-styled form, both in length and in th6 

 structure of the stigma. Hence the self-union of this variety is, 

 in fact, a legitimate union, and consequently is highly fertile. 

 Mr. Scott further states that this variety yielded very few seeds 

 when fertilised by either the long- or short-styled common 

 cowslip, and, again, that both forms of the latter, when fertilised 

 by the equal-styled variety, likwise produced very few seeds. 

 But his experiments with the cowslip were few, and my results 

 do not confirm his in any uniform manner. 



I raised twenty plants from self-fertilised seed sent me by Mr. 

 Scott ; and they all produced red flowers, varying slightly in 

 tint. Of these, two were strictly long-styled both in structure 

 and in function; for their reproductive powers were tested by 

 crosses with both forms of the common cowslip. Six plants 

 were equal-styled ; but on the same plant the pistil varied a 

 good deal in length during different seasons. This was likewise 

 the case, according to Mr. Scott, with the parent-plant. Lastly, 

 twelve plants were in appearance short-styled ; but they varied 

 much more in the length of their pistils than ordinary short- 

 styled cowslips, and they differed widely from the latter in 

 their powers of reproduction. Their pistils had become short- 

 styled in structure, whilst remaining long-styled in function. 

 Short-styled cowslips, when insects are excluded, are extremely 

 barren : for instance, on one occasion six fine plants produced 

 only about 50 seeds (that is, less than the product of two good 

 capsules), and on another occasion not a single capsule. Now, 

 when the above twelve apparently short-styled seedlings were 

 similarly treated, nearly all produced a great abundance of 

 capsules, containing numerous seeds, f which germinated re- 

 markably well. Moreover three of these plants, which during 

 the first year were furnished with quite short pistils, on the 

 following year produced pistils of extraordinary length. The 

 greater number, therefore, of these short-styled plants could not 

 be distinguished in function from the equal-styled variety. The 

 anthers in the six equal-styled and in the apparently twelve 

 short-styled plants were seated high up in the corolla, as in the 

 true short-styled cowslip; and the pollen-grains resembled 

 those of the same form in their large size, but were mingled 



