84 DARWINISM chap. 



countenance, almost as varied when closely studied as that of 

 a human being; not only can a shepherd distinguish every 

 sheep in his flock, but we all know that each kitten in the 

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

 o«Ti, Avith an expression and indi^dduality distinct from all 

 its brothers and sisters. Now this individual variability 

 exists among all creatures whatever, which Ave 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 floAvers or of vegetables we shall find, if we look 

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

 in the mode of groAvth, in the shape or coloiu' of the leaves, 

 in the form, coloiu", or markings of the floAvers, 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 A'ery 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 A^aria- 

 tions can be increased to an enormous extent — apparently to 

 any extent not incompatible Avith the life, gTOAvth, and re- 

 production of the plant or animal. 



The AA-ay this is done is by artificial selection, and it is 

 very important to understand this process and its results. 

 Suppose we have a plant AA'ith a small edible seed, and we 

 AA'ant to increase the size of that seed. AVe groAv as large a 

 C|uantity of it as possible, and AA'hen the crop is ripe Ave 

 carefully choose a feAv of the A^ery largest seeds, or we may 

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

 Next year Ave soav only these large seeds, taking care to giA^e 

 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 noAv somewhat larger and 

 more numerous. Again soAving these, we obtain a further 

 slight increase of size, and in a A'ery feAv years Ave obtain a 

 greatly improved race, AA^hich Avill ah^'ays produce larger seeds 

 than the unimproved race, even if cultivated AA-ithout any 

 special care. In this AA^ay all our fine sorts of A'egetables, 

 fruits, and floAvers have been obtained, all oiu' choice breeds 



