Introductory. 19 



An extensive retail bookstore furnishes an object lesson 

 in classification, thougli 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 jManual of Botany, 

 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 different classes of books, 

 as scientific books, books of fiction, etc., would corres- 

 pond to families. There would als(j be copies of the 

 same woi-k in different bindings which would coriespond 

 to varieties. 



22. Scientific Names are given to plants and animals 

 because the common names by which they are known are 

 so often local. For example, quack grass, one of our 

 common troublesome weeds, is known by at least seven 



* It should not, however, be understood that the diflferent species 

 of plants and animals are always as readily distinguished as are the 

 different works in a bookstore. 



