CHAP. VI. PRIMULA VERIS. 219 



48-20, and that of the six self-fertilised plants 33 -23 ; or as 100 

 to 69. 



These six crossed plants produced spontaneously twenty-six 

 capsules, whilst the six self-fertilised plants produced only two, 

 or as 100 to 8. There is therefore the same extraordinary 

 difference in fertility between the crossed and self-fertilised 

 plants as in the last genus, Cyclamen, which belongs to the same 

 family of the Primulacefe. 



PBIMULA VERIS. Brit. Flora. 

 (Far. officinalis, Linn.). The Cowslip. 



Most of the species in this genus are heterostyled or 

 dimorphic ; that is, they present two forms, one long-styled 

 with short stamens, and the other short-styled with long 

 stamens.* For complete fertilisation it is necessary that 

 pollen from the one form should be applied to the stigma 

 of the other form ; and this is effected under nature by insects. 

 Such unions, and the seedlings raised from them, I have 

 called legitimate. If one form is fertilised with pollen 

 from the same form, the full complement of seed is not pro- 

 duced ; and in the case of some heterostyled genera no seed at 

 all is produced. Such unions, and the seedlings raised from 

 them, I have called illegitimate. These seedlings are often 

 dwarfed and more or less sterile, like hybrids. I possessed 

 some long-styled plants of P. veris, which during four successive 

 generations had been produced from illegitimate unions be- 

 tween long-styled plants ; they were, moreover, in some degree 

 inter-related, and had been subjected all the time to similar 

 conditions in pots in the greenhouse. As long as they were 

 cultivated in this manner, they grew well and were healthy and 

 fertile. Their fertility even increased in the later generations, 

 as if they were becoming habituated to illegitimate fertilisation. 

 Plants of the first illegitimate generation when taken from the 

 greenhouse and planted in moderately good soil out of doors 

 grew well and were healthy ; but when those of the two last 

 illegitimate generations were thus treated they became exces- 

 sively sterile and dwarfed, and remained so during the following 



* See my work, ' The Different papers in ' Journal of Proc. Linn 

 Forms of Flowers on Plants of Soc.' vol. vi. 1862, p. 77, and vol 

 the same Species/ 1877, or my x. 1867, p. 393. 



