CHAP. II. THE COMMON OXLIP. 59 



were, I may remind the reader that 90 per cent, of the 

 flowers of the primrose fertilised legitimately with 

 primrose-pollen yielded capsules, containing on an 

 average 66 seeds; and that 54 per cent, of the flowers 

 fertilised illegitimately yielded capsules containing on 

 an average 3.55 seeds per capsule. The primrose, 

 especially the short-styled form, when fertilised by the 

 cowslip, is less sterile, as Gartner likewise observed, 

 than is the cowslip when fertilised by the primrose. 

 The above experiments also show that a cross between 

 the same forms of the primrose and cowslip is much 

 more sterile than that between different forms of these 

 two species. 



The seeds from the several foregoing crosses were 

 sown, but none germinated except those from the 

 short-styled primrose fertilised with pollen of the 

 polyanthus; and these seeds were the finest of the 

 whole lot. I thus raised six plants, and compared them 

 with a group of wild oxlips which I had trans- 

 planted into my garden. One of these wild oxlips 

 produced slightly larger flowers than the others, and 

 this one was identical in every character (in foliage, 

 flower-peduncle, and flowers) with my six plants, 

 excepting that the flowers of the latter were tinged of 

 a dingy red colour, from being descended from the 

 polyanthus. 



We thus see that the cowslip and primrose can- 

 not be crossed either way except with considerable 

 difficulty, that they differ conspicuously in external 

 appearance, that they differ in various physiological 



illegitimately with pollen of the 22.6 seeds. On the other hand, 

 cowslip gave five capsules, contain- the seeds produced by the poly- 

 ing on an average 32.4 seeds ; anthus-pollen were much the fin- 

 whilst 18 flowers similarly ferti- est of the whole lot, and were the 

 lised by polyanthus-pollen yielded only ones which germinated, 

 only five capsules, containing only 



