Introductory. 19 



apple, pear and quince, and the one containing the 

 plum, cherry and peach, are formed into other groups 

 called families.* Thus families are made up of genera, 

 and genera are made up of species. There may be, also, 

 different varieties in the same species, as the different 

 varieties of apple, pea, or strawberry. 



An extensive retail bookstore furnishes an object les- 

 son in classification, though we must remember that in 

 natural history it is usually the names and descriptions 

 of plants and animals that are classified, and not the 

 plants and animals themselves. In the bookstore, we 

 will observe that the books are not placed upon the 

 shelves without order, but that they are arranged in 

 groups. Different copies of the same work are placed 

 together. Different works on the same subject, as 

 Gray's botany, Wood's botany, Bessey's botany are also 

 placed in a larger group. Then all the scientific books 

 are formed into a still larger group, as are the books of 

 fiction, the books of poetry, the music books, etc. Com- 

 paring this arrangement with that employed in natural 

 history, each separate work, as Gray's Manual of Bot- 

 any, Thomas' Fruit Culturist, Bunyan's Pilgrim's 

 Progress, etc., would correspond to a species,! and the 

 different copies of the same work would correspond to 

 individuals. The books treating of the same general 

 subject, as the different works on geology, botany or 

 arithmetic would correspond to genera, and the differ- 

 ent classes of books, as scientific books, books of fiction, 



* Related families are often further united into orders. 



t It should not. however, be understood that the different spe- 

 cies of plants and animals are always as readily distinguished as 

 are the different works in a bookstore. 



