Chap. III. PULMONAEIA OFFICINALIS. 103 



illegitimately fertilised plant must have produced about 

 100 seeds; that is, thrice as many as one of the wild 

 long-styled plants collected on the Siebengebirge by 

 Hildebrand, and which, no doubt, had been legitimately 

 fertilised. In the following year one of my plants 

 was covered by a net, and even under these un- 

 favourable conditions it produced spontaneously a 

 few seeds. It should be observed that as the flowers 

 stand either almost horizontally or hang considerably 

 downwards, pollen from the short stamens would be 

 likely to fall on the stigma. We thus see that the 

 English long-styled plants when illegitimately ferti- 

 lised were highly fertile, whilst the German plants 

 similarly treated by Hildebrand were completely 

 sterile. How to account for this wide discordance in 

 our results I know not. Hildebrand cultivated his 

 plants in pots and kept them' for a time in the house, 

 whilst mine were grown out of doors; and he thinks 

 that this difference of treatment may have caused the 

 difference in our results. But this does not appear to 

 me nearly a sufficient cause, arlthough his plants were 

 slightly less productive than the wild ones growing 

 on the Siebengebirge. My plants exhibited no ten- 

 dency to become equal-styled, so as to lose their proper 

 long-styled character, as not rarely happens under 

 cultivation with several heterostyled species of Pri- 

 mula; but it would appear that they had been greatly 

 affected in function, either by long-continued cultiva- 

 tion or by some other cause. We shall see in a 

 future chapter that heterostyled plants illegitimately 

 fertilised during several successive generations some- 

 times become more self -fertile; and this may have been 

 the case with my stock of the present species of Pul- 

 monaria; but in this case we must assume that the 

 long-styled plants were at first sufficiently fertile to 

 9 



