24 USES OF CLASSIFICATION. 



structure ; but the botanist is now aware, that many forms exi^t, 

 which are intermediate between these, and that all may be raised 

 from one stock. The same is the case with many other kinds of 

 Plants. 



17. This explanation, will, it is hoped, make the meaning of 

 the term species understood ; and it is very desirable that clear 

 notions on the subject should be a-cquired by the student of 

 Natural History at the very commencement of his attention to 

 the pursuit. It is computed that from 70,000 to 80,000 distinct 

 species of Plants have been collected by Botanists from the 

 surface of the globe ; and probably at least as many more remain 

 to be discovered. It is obvious that an acquaintance with the 

 structure and characters of such a vast number of different races, 

 will be rendered much easier by classifying or arranging them, 

 placing those together, which have a greater or less amount of 

 general resemblance ; and separating others, according to their 

 amount of difference. It is only in this manner, indeed, that 

 any one, within the compass of a single life, can become master 

 of the whole. In making such an arrangement, those species are 

 first assembled into a group, termed a yenus, which resemble 

 each other in all the more important particulars, and differ only 

 in minor details. For example, the different kinds of Roses among 

 plants, and the Lion, Tiger, Leopard, and other species of the 

 Cat kind among animals, are considered as belonging to the same 

 genus, their points of agreement being far more numerous than 

 those of difference. Several genera may, in like manner, be 

 united into a family; the various members of which have a 

 common resemblance, though with many subordinate differences. 

 By continuing to pursue the same plan, we form divisions of 

 greater and greater extent ; until we are at last brought, by 

 uniting subordinate ones, to the primary divisions, into which 

 the whole kingdom may be at once distributed ; each of which 

 divisions contains a large number of very dissimilar groups, 

 united together by some common points of general resemblance. 



1 8. Perhaps an illustration may make this subject better un- 

 derstood. If we were to examine the people of any nation, in 

 which there had been but little intermixture among its different 



