140 APPLIED BIOLOGY 



larity of form, manners, language, etc., we naturally classify 

 the families as members of the same nation. And we think 

 of Germans, French, English, and Swedish nations as belong- 

 ing to the white race ; and we think of Chinese and Japanese 

 as belonging to a different race. Also we classify men accord- 

 ing to their political and religious beliefs and their business 

 in life. When we stop to consider the matter, it becomes 

 evident that we are all the time classifying things which in- 

 terest us in everyday life. 



Now, naturalists (biologists) have followed the same tend- 

 ency in grouping similar animals and plants. Noting that 

 dogs and wolves and foxes are very much alike, naturalists 

 have long regarded these animals as in one family, just as we 

 think of two similar human individuals as in the same family. 

 And then, noting that the members of other families of ani- 

 mals (e.g., bear and raccoon) have some of the same char- 

 acteristics, naturalists have united the families into an order, 

 just as we unite similar human families into nations. And 

 orders are united into classes, as nations into races of men. 

 In some such way naturalists have been at work from before 

 the days of Aristotle (B.C., 384-322), who wrote the first 

 books on animals and plants, and they have gradually grouped 

 similar forms together into species, genera, families, orders, 

 and larger groups. Many of these groups are not yet com- 

 plete, for many animals and plants have not yet been studied 

 carefully enough to show what other species they most closely 

 resemble. 



Another reason for classification is that it is convenient for 

 references, just as in a library it is useful to have all the books 

 on a given subject placed together. Since there are several 

 hundred thousand species of animals and plants, it would 

 be quite impossible to find the descriptions and names if we 

 had no classification. But with classification identification 

 is easy. A new animal was found in Africa recently. It 

 had a backbone, and was therefore a vertebrate. It had 



