46 HETEROSTYLED DIMORPHIC PLANTS. CRAP. I 



TABLE 12. 



Summary on the Fertility of the two Legitimate Unions, compared 

 with that of the two Illegitimate Unions, in the genus Primula. 

 The former taken at 100. 



Average of the nine species 



88-4 



61-8 



With plants of all kinds some flowers generally fail 

 to produce capsules, from various accidental causes ; 

 but this source of error has been eliminated, as far as 

 possible, in all the previous cases, by the manner in 

 which the calculations have been made. Supposing, 

 for instance, that 20 flowers were fertilised legiti- 

 mately and yielded 18 capsules, and that 30 flowers 

 were fertilised illegitimately and yielded 15 cap- 

 sules, we may assume that on an average an equal 

 proportion of the flowers in both lots would fail to 

 produce capsules from various accidental causes ; and 

 the ratio of to }$, or as 100 to 56 (in whole 



