74 HYBRID PRIMULAS. CHAP. IL 



crossing other heterostyled species of Primula.* I 

 have already alluded to his statement, that in four 

 instances (not to mention others) a species when crossed 

 with a distinct one yielded a larger number of seeds 

 than the same species fertilised illegitimately with its 

 own-form pollen, though taken from a distinct plant. 

 It has long been known from the researches of Kolreuter 

 and Gartner, that two species when crossed reciprocally 

 sometimes differ as widely as is possible in their fer- 

 tility : thus A when crossed with the pollen of B will 

 yield a large number of seeds, whilst B may be crossed 

 repeatedly with pollen of A, and will never yield a single 

 seed. Now Mr. Scott shows in several cases that the 

 same law holds good when two heterostyled species 

 of Primula are intercrossed, or when one is crossed 

 with a homostyled species. But the results are much 

 more complicated than with ordinary plants, as two 

 heterostyled dimorphic species can be intercrossed in 

 eight different ways. I will give one instance from 

 Mr. Scott. The long-styled P. hirsuta fertilised legi- 

 timately and illegitimately with pollen from the two 

 forms of P. auricula, and reciprocally the long-styled 

 P. auricula fertilised legitimately and illegitimately 

 with pollen from the two forms of P. hirsuta, did 

 not produce a single seed. Nor did the short- 

 styled P. hirsuta when fertilised legitimately and 

 illegitimately with the pollen of the two forms of 

 P. auricula. On the other hand, the short-styled 

 P. auricula fertilised with pollen from the long-styled 

 P. hirsuta yielded capsules containing on an average 

 no less than 56 seeds ; and the short-styled P. 

 auricula by pollen of the short-styled P. hirsuta 

 yielded capsules containing on an average 42 seeds 



' Jouru. Linn. Soc.Bot.' vol. viii. 1864, p. 93 to end. 



