XVI.] THE LAWS OF VARIATION. 193 



no doubt, not only by bringing pollen from other flowers, 

 but also, in those flowers which are capable of being 

 fertilized by their own pollen, by brushing it on to the 

 stigma ; and it is probably impossible in all cases to 

 separate these two functions ; but, after what has been 

 said, we cannot doubt that the occasional introduction of 

 pollen from another flower must be beneficial. Pollen 

 will, no doubt, be brought from flowers of other species ; 

 but this will not be injurious — it will have no effect 

 whatever. 



Sexuality, and the existence of distinct generative organs, Sexuality 

 are not the same thing, and do not imply each other. The fromThe 

 existence of separate generative organs is only a case of existence 

 the " physiological division of labour," in virtue of which generative 

 law every separate function in the ascending scale of°^"S^"^- 

 organization tends to acquire a separate organ for itself. 

 There are many cases of the action of the reproductive 

 fimction through distinct reproductive organs without the 

 sexual relation coming into play : the females of some 

 butterflies, for instance, produce true eggs from true ovaries, 

 which are fertile Avithout being fertilized by the male.^ 

 And, on the other hand, the instance of the lower Algfe, 

 mentioned above, shows that sexuality may exist without 

 separate reproductive organs, or even distinction of sexes ; 

 and that it essentially consists in the union and fusion 

 of germinal matter from two distinct sources. It con- 

 sequently appears a highly probable conclusion, that sex- 

 uahty, though a universal law of life, is not an ultimate depends 

 one, but is to be referred to the necessity for slight changes, necessity 

 in order to keep up the vigour of life. Many of the lower of slight 

 organisms, no doubt, propagate by spontaneous division, as 

 the simpler Algee ; others, by throwing off buds, as the 

 Hydra ; others, which are not so lowly organized, by true 

 eggs that have not been fertilized by the male, as the 

 butterflies just mentioned ; and others are capable of fer- 

 tilizing themselves by a truly sexual process, like many 

 flowers. But it appears probable that no organic species 



^ Spencer's Pi-inciples of Biology, vol. ii. p. 214. 

 



