430 NINETEENTH CENTURY. pt. hi. 



seed and to multiply. And so you see that it actually de- 

 pends upon the number of cats in the neighbourhood how 

 many of these flowers there are growing in our fields. 



But now let us suppose for a moment that among the 

 field-mice there are some whose skin has a slightly peculiar 

 smell, so that the cats do not eat them when they can find 

 others. Clearly these mice would live longest and have most 

 offspring ; and of these again, those with strong-smelling skins 

 would live ; and so after a time a new race of mice would 

 arise which would be independent of the cats, and the bees 

 would have a poor chance of living, and consequently the 

 flowers of bearing seeds. 



But this might in the end give rise to quite a new race 

 of plants, for it is believed that some moths would visit the 

 clovers, only as Mr. Darwin points out, they are not heavy 

 enough to weigh down the petals of the flowers so as to 

 creep inside them. But as no two flowers are ever exactly 

 alike, it is very likely that the petals of some blossoms will 

 droop a little more than in the others, and so if the bees 

 became scarce, these blossoms with drooping petals might 

 live on, because the moths could creep into them and carry 

 their pollen from flower to flower ; and thus a new race of 

 clover with drooping petals might spring up independent of 

 the cats, the mice, and the bees, and would become a new 

 species. 



You must especially notice in this imaginary example 

 that it is only useful variations which can be passed on 

 from generation to generation. If the smell of the mice 

 (which would probably come from some peculiarity in the 

 pores of the skin) did not preserve them from the cats, the 

 strong- smelling mice would not live, and a peculiar race 

 would not arise ; in the same way, if the drooping leaves of 





