4 INTRODUCTION. 



preserve, and accumulate the variations given to him by the 

 hand of nature almost in any way which he chooses ; and 

 thus he can certainly produce a great result. Selection may 

 be followed either methodically and intentionally, or uncon- 

 sciously and unintentionally. Man may select and preserve 

 each successive variation, with the distinct intention of im- 

 proving and altering a breed, in accordance with a precon- 

 ceived idea; and by thus adding up variations, often so 

 slight as to be imperceptible by an uneducated eye, he has 

 effected wonderful changes and improvements. It can, also, 

 be clearly shown that man, without any intention or thought 

 of improving the breed, by preserving in each successive 

 generation the individuals which he prizes most, and by 

 destroying the worthless individuals, slowly, though surely, 

 induces great changes. As the will of man thus comes 

 into play, we can understand how it is that domesticated 

 breeds show adaptation to his wants and pleasures. We 

 can further understand how it is that domestic races of 

 animals and cultivated races of plants often exhibit an 

 abnormal character, as compared with natural species ; for 

 they have been modified not for their own benefit, but for 

 that of man. 



In another work I shall discuss, if time and health permit, 

 the variability of organic beings in a state of nature ; namely, 

 the individual differences presented by animals and plants, 

 and those slightly greater and generally inherited differences 

 which are ranked by naturalists as varieties or geographical 

 races. We shall see how difficult, or rather how impossible 

 it often is, to distinguish between races and sub-species, as 

 the less well-marked forms have sometimes been denominated ; 

 and again between sub-species and true species. I shall 

 further attempt to show that it is the common and widely 

 ranging, or, as they may be called, the dominant species, 

 which most frequently vary ; and that it is the large and 

 flourishing genera which include the greatest number of 

 varying species. Varieties, as we shall see, may justly be 

 called incipient species. 



But it may be urged, granting that organic beings in a state 

 of nature present seme varieties, — that their organization is 



