84 DARWINISM 



countenance, almost as varied when closely studied as that of 

 a human being ; not only can a shepherd distinguish every 

 shee}> in his flock, but we all know that each kitten in the 

 successive families of our old favourite cat has a face of its 

 own, with an expression and individuality distinct from all 

 its brothers and sisters. Now this individual variability 

 exists among all creatures whatever, Avhich we can closely 

 observe, even when the two parents are very much alike and 

 have been matched in order to preserve some special breed. 

 The same thing occurs in the vegetable kingdom. All plants 

 raised from seed differ more or less from each other. In 

 every bed of flowers or of vegetables we shall find, if we look 

 closely, that there are countless small differences, in the size, 

 in the mode of growth, in the shape or colour of the leaves, 

 in the form, colour, or markings of the flowers, or in the size, 

 form, colour, or flavour of the fruit. These differences are 

 usually small, but are yet easily seen, and in their extremes 

 are very considerable ; and they have this important quality, 

 that they have a tendency to be reproduced, and thus by 

 careful breeding any particular variation or group of varia- 

 tions can be increased to an enormous extent — apparently to 

 any extent not incompatible with the life, growth, and re- 

 production of the plant or animal. 



The way this is done is by artificial selection, and it is 

 Very important to understand this process and its results. 

 Suppose we have a plant with a small edible seed, and we 

 want to increase the size of that seed. AVe grow as large a 

 quantity of it as possible, and when the crop is ripe we 

 carefully choose a few of the very largest seeds, or we may 

 by means of a sieve sort out a quantity of the largest seeds. 

 Next year we sow only these large seeds, taking care to give 

 them suitable soil and manure, and the result is found to be 

 that the average size of the seeds is larger than in the first 

 crop, and that the largest seeds are now somewhat larger and 

 more numerous. Again so^^^ng these, we obtain a further 

 slight increase of size, and in a very few years we obtain a 

 greatly improved race, which will always produce larger seeds 

 than the unimproved race, even if cultivated without any 

 special care. In this way all our fine sorts of vegetables, 

 fruits, and flowers have been obtained, all our choice breeds 



