440 MR. C. DABWIN ON SPECiriC DirFEBENCES IN PRIMULA. 



styled flowers of the Primrose were legitimately crossed with 

 pollen of the Cowslip and Polyanthus, and, together, they yielded 

 six capsules, containing on an average 37 seeds, some of fine quality 

 and some only moderately good. The pure Primrose, when legi- 

 timately fertilized by pollen from the Primrose, yields an average 

 of almost exactly double this number of seeds, viz. 71. Lastly, 

 eight long-styled and seven short-styled flowers of the Primrose 

 were illegitimatelyi fertilized by pollen of the Cowslip and Poly- 

 anthus, and, together, they yielded only four capsules, containing 

 on an average only 13 seeds, some good and some poor. The 

 Primrose, when illegitimately fertilized by pollen from the Prim- 

 rose, yields an average of about 44 seeds. We thus see that a cross 

 between the same forms of the Primrose and Cowslip is far more 

 sterile than a cross between the opposite forms. The Primrose, 

 especially the short-styled form, when fertilized by the Cowslip, is 

 less sterile, as Gartner likewise observed, than the Cowslip when 

 reciprocally fertilized by the Primrose. 



I sowed the seeds produced from the several foregoing crosses ; 

 but none germinated except those from the short-styled Primrose 

 fertilized by the 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, evidently produced from 

 the same capsule, which I had transplanted 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, ex- 

 cepting that the flowers in the latter were tinged of a dirty red 

 colour, 



r 



We have now seen that the Cowslip and Primrose cannot be 

 crossed either way except with considerable difficulty, that they 

 differ conspicuously in external appearance, that they differ in 

 certain curious physiological characters, that they inhabit slightly 

 diff"erent stations and range differently. Hence those botanists 

 who rank these plants as varieties ought to be able to prove that 

 they are not as well fixed in character as are most species ; 

 and the evidence in favour of such instability of character does 

 appear at first very strong. It rests, first, on statements made 

 by several competent observers that from seeds of the same 

 plant they have raised Cowslips, Primroses, and Oxlips ; and, 

 secondly, on the frequent occurrence in a state of nature of plants 

 presenting every intermediate gradation between the Cowslip and 

 Pidmrose. 



