IN THE SPECIES OF PBIMULA. bS 



These figures, reduced as before, give the following proportions : — 





Number 

 of 



Plants. 



Weight of 

 seed in 

 graiaa. 



Number 



of 

 Umbels. 



Weight of 

 seed in 

 grains. 



Short-styled Cowslips . . . 

 Long-styled Cowslips . . . 



100 

 100 



1585 

 1093 



100 

 100 



4.30 

 332 



The season was much better this year than the last, and the 

 plants grew in good soil, instead of in a shady wood or struggling 

 with other plants in the open field ; consequently the actual pro- 

 duce of seed was considerably greater. Nevertheless we have the 

 same relative result ; for the short-styled plants produced more 

 seed than the long-styled in the proportion of tliree to two ; but if 

 we take the fairest standard of comparison, namely, the number of 

 umbels, the excess is, as in the former case, as four to three. 



I marked also some Primroses, all growing together under the 

 same conditions ; and we here see the product ; — 





No. of 

 Plants. 



Total 

 So. of 

 Cap- 

 sules. 



Good -y'S''^ 



Cap- i°f?™<' 



sules. 1 '^ 



! grains. 



Or by Calcu- 

 lation '• 



Good 

 Cap- 

 sules. 



1 

 Weight 



seed. 



Short-styled Primroses 

 Long-styled Primroses 



8 

 9 



49 



68 



40 



50 



16 

 10 



100 

 100 



40 

 20 



The number of Primrose plants tried was hardly sufficient, and 

 the season was bad ; but we here again see (excluding the capsules 

 which contained no seed) the same result in a still more marked 

 manner, for the short-styled plants were twice as productive of 

 seed as the long-styled plants. 



I had, of course, no means of ascertaining the relative fertility of 

 the two forms of the Chinese Primrose in a natural condition, and 

 the result of artificial fertilization can hardly be trusted ; but sis- 

 teen capsules from long-styled flowers, properly fertilized, produce 

 9'3 grains' weight of seed, whereas eight capsules of short-styled 

 flowers produced 61 grains ; so that if the same number, namely, 

 16 of the latter, had been fertilized, the weight of seed would have 

 been 12'2, which would have been nearly in the proportion of four 

 to three, as in Cowslips. 



Looking to the trials made during two successive years on the 

 large number of Cowslips, and on these facts with regard to com- 

 mon Primroses and Chinese Primroses, we may safely conclude 

 that the short-styled forms in these species are more productive 



G 2 



