224 ILLEGITIMATE OPPSPEHSTG OF Chap. V. 



that the short-styled form is not rendered quite sterile by a 

 long course of fertilisation with pollen of the same form ; but as 

 there would always be some liability to an occasional cross with 

 the other form, we cannot tell how long self-fertilisation has 

 been continued. 



Peimula fabinosa. 



Mr. Scott says* that it is not at all uncommon to find equal- 

 styled plants of this heterostyled species. Judging from the 

 size of the pollen-grains, these plants owe their structure, as in 

 the case of P. awricula, to the abnormal elongation of the 

 stamens of the long-styled form. In accordance with this view, 

 they yield less seed when crossed with the long-styled form 

 than with the short-styled. But they differ in an anomalous 

 manner from the equal-styled plants of P. auricula in being 

 extremely sterile with their own pollen. 



Pkimula blatiob. 



It was shown in the first chapter, on the authority of 

 Herr Breitenbach, that equal-styled flowers are occasionally 

 found on this species whilst growing in a state of nature ; and 

 this is the only instance of such an occurrence known to me, 

 with the exception of some wild plants of the Oxlip — a hybrid 

 between P. veris and vulgaris — which were equal-styled. Herr 

 Breitenbach's case is remarkable in another way; for equal- 

 styled flowers were found in two instances on plants which bore 

 both long-styled and short-styled flowers. In every other 

 instance these two forms and the equal-styled variety have been 

 produced by distinct plants. 



Peimula vtjlgaeis, Brit. Fl. 

 Var. acauUs of Linn, and P. aeaulis of J acq. 



Var. rubra. — Mr. Scott states t that this variety, which 

 grew in the Botanic Garden in Edinburgh, was quite 

 sterile when fertilised with pollen from the common 

 primrose, as well as from a white yariety of the same 



* ' Journal Proo. Linn. Soo.' vlii. (1864), p. 115. 

 t Ibid. p. 98. 



