Chap. XVI. FROM DOMESTICATION. 113 



that it is difficult to estimate them; but on comparing bods of carrots 

 saved for seed in a nursery garden with wild plants, the former seemed 

 to produce about twice as much seed. Cultivated cabbages yielded 

 thrice as many pods by measure as wild cabbages from the rocks of 

 South Wales. The excess of berries produced by the cultivated Aspa- 

 ragus in comparison with the wild plant is enormous. No doubt many 

 highly cultivated plants, such as pears, pineapples, bananas, sugar-cane, 

 &c, are nearly or quite sterile; and I am inclined to attribute this 

 sterility to excess of food and to other unnatural conditions ; but to this 

 subject I shall presently recur. 



In some cases, as with the pig, rabbit, &c., and with those 

 plants which are valued for their seed, the direct selection of 

 the more fertile individuals has probably much increased their 

 fertility ; and in all cases this may have occurred indirectly, from 

 the better chance of the more numerous offspring produced by 

 the more fertile individuals having survived. But with cats, 

 ferrets, and clogs, and with plants like carrots, cabbages, and 

 asparagus, which are not valued for their prolificacy, selection 

 can have played only a subordinate part ; and their increased 

 fertility must be attributed to the more favourable conditions of 

 life under which they have long existed. 



VOL. II. 



