Chap. IV.] DIVERGENCE OP CHARACTER. 137 



change in conditions) only by its varying descendants 

 seizing on places at present occupied by other animals: 

 some of them, for instance, being enabled to feed on new 

 kinds of prey, either dead or alive; some inhabiting new 

 stations, climbing trees, frequenting water, and some 

 perhaps becoming less carnivorous. The more diver- 

 sified in habits and structure the descendants of our 

 carnivorous animals become, the more places they will 

 be enabled to occupy. What applies to one animal will 

 apply throughout all time to all animals — that is, if they 

 vary — for otherwise natural selection can affect nothing. 

 So it will be with plants. It has been experimentally 

 proved, that if a plot of ground be sown with one species 

 of grass, and a similar plot be sown with several distinct 

 genera of grasses, a greater number of plants and a 

 greater weight of dry herbage can be raised in the latter 

 than in the former case. The same has been found to 

 hold good when one variety and several mixed varieties 

 of wheat have been sown on equal spaces of ground. 

 Hence, if any one species of grass were to go on varying, 

 and the varieties were continually selected which dif- 

 fered from each other in the same manner, though in a 

 very slight degree, as do the distinct species and genera 

 of grasses, a greater number of individual plants of this 

 species, including its modified descendants, would suc- 

 ceed in living on the same piece of ground. And we 

 know that each species and each variety of grass is annu- 

 ally sowing almost countless seeds; and is thus striv- 

 ing, as it may be said, to the utmost to increase in num- 

 ber. Consequently, in the course of many thousand 

 generations, the most distinct varieties of any one species 

 of grass would have the best chance of succeeding and 

 of increasing in numbers, and thus of supplanting the 



