THE FERTILISATION OF F LOWERS. 



y-i 



the former conceptions of a " species," as a group the members of 

 which were fertile inter se, but infertile with members even of nearly 

 allied species ; and such knowledge supplies a wholesome corrective 

 to the theory that species are separate, independent, and distinct 

 entities both as to origin and after-relations. 



If nature contrives by such means to effect cross-fertilisation, there 

 exist ample fields for the demonstration of a like result in other and 



FIG. 227. ARUM, OR CUCKOO PINT. 



FIG. 228. CARNATION, SHOWING THE RIPE PISTIL 



very varied fashions. In a very large number of flowers, for instance, 

 the stamens ripen and discharge their pollen before the pistil is ripe, or 

 the ovules ready for fertilisation. In other cases, but more rarely, the 

 pistil ripens before the stamens. The former case is illustrated by 

 most species of geraniums, pelargoniums, by harebells, and other 

 Camfanulacece (Fig. 214), by many umbelliferous plants, by carnations 



