CHAPTER TWENTY-TWO 



THE PRINCIPLES OF CLASSIFICATION 



I. WHEN we contemplate the enormous bulk of Necessity 

 scientific literature, and the multitude of facts dis- 

 covered and recorded by scientific men, it seems as if 

 science must eventually be smothered by its own mass. 

 Yet those who have long engaged in scientific pursuits 

 know that, on the contrary, it is becoming easier to deal 

 with the accumulating materials. The secret of this is 

 classification, the putting in order of our data so that 

 each item can be found where it belongs. This is not 

 peculiar to science. Although there are hundreds of 

 millions of people in the world, a letter mailed in the 

 Philippine Islands reaches a particular individual in 

 Colorado, requiring only five words on the envelope in 

 addition to the name. The reader of these lines has a 

 name, and presumably lives in a particular house, on 

 a particular street, in a particular town, situated in a 

 particular county of a particular state of the United 

 States. All these things being known and named, that 

 individual can be found without any difficulty. So it is 

 with the zoological or botanical classification. The 

 reader is probably an American, he is a member of the 

 species Homo sapiens, which is included in genus Homo, 

 which falls in the family Hominidae, which belongs to 

 the Mammalia, these in turn being Vertebrata, which 

 are Animalia or animals. 



2. Suppose for a moment that some being from Significance 

 another world has come here and captured a man. He 

 is acquainted with zoological methods, and desires to 

 find out what the strange creature may be. His reason- 

 ing will be somewhat as follows : Obviously, at the out- 

 set, this is an animal, not a plant. It has a vertebral 



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