58 HYBRID PEIMULAS. Chap. It 



hare like distinct species, for they are far from 

 being mutually fertile. Gartner* crossed 27 flowers 

 of P. vulgaris with pollen of P. veris, and obtained 

 16 capsules; but these did not contain any good 

 seed. He also crossed 21 flowers of P. veris with 

 pollen of P. vvlgaris ; and now he got only fire 

 capsules, containing seed in a still less perfect 

 condition. Gartner knew nothing about hetero- 

 stylism; and his complete failure may perhaps be 

 accounted for by his haying crossed together the 

 same forms of the cowslip and primrose ; for such 

 crosses would haye been of an illegitimate as well as 

 of a hybrid nature, and this would have increased 

 their sterility. My trials were rather more fortunate. 

 Twenty-one flowers, consisting of both forms of the 

 cowslip and primrose, were intercrossed legitimately, 

 and yielded seven capsules {i.e. 33 per cent.), contain- 

 ing on an average 42 seeds; some of these seeds, 

 however, were so poor that they probably would not have 

 germinated. Twenty-one flowers on the same cowslip 

 and primrose plants were also intercrossed illegiti- 

 mately, and they likewise yielded seven capsules (or 

 33 per cent.), but these contained on an average only 

 13 good and bad seeds. I should, however, state that 

 some of the above flowers of the primrose were fertilised 

 with pollen from the polyanthus, which is certainly a 

 variety of the cowslip, as may be inferred from the per- 

 fect fertility inter se of the crossed offspring from these 

 two plants. t To show how sterile these hybrid unions 



* ' Bastarderzeugung,' 1849, p. ciently numerous. The degree of 



721. infertility of a cross is liable to 



t Mr. Scott has discnased the much fluctuation. Pollen from 

 nature of the polyanthus {'Proo. the cowslip at first appears rather 

 Linn. Soc' viii. Bot. 1864, p. moreefficient ontheprimrose than 

 103), and arrives at a different that of the polyanthus ; for 12 

 conclusion ; but I do not think flowers of both forms of the prim- 

 that his experiments were siiffl- rose, fertilised legitimately and 



