CHAPTER 6 



ORDERLINESS 

 AMONG ANIMALS 



Nearly all of the earth's thin crust is 

 teeming with plant and animal life, each 

 fitted by form and habit to its particular 

 niche. Yet within this wide variety there 

 exists a uniformity of structure and behav- 

 ior that is recognized by anyone who has 

 taken the time to make even casual obser- 

 vations. Such facts as the shape of fast- 

 swimming animals, the warm blood and fur 

 of mammals, the feathers of birds, all point 

 to a uniformity of design which indicates 

 basic kinships that were early recognized 

 by men interested in natural history. Fol- 

 lowing man's innate tendency to catalog 

 everything about him when it exists in 

 sufficient numbers, animals were grouped 

 according to similarities in structure, habit, 

 and environment. 



The first schemes for classifying animals 

 were based on convenience alone. Animals 

 were simply put into groups in order to 

 prevent confusion, the method of catalog- 

 ing resembling the design of present-day 

 telephone directories. This system served 

 the single purpose of arranging animals so 

 that one might conveniently find the name 

 of any one of them. Animals were classified 

 according to their environments: those liv- 

 ing in water, in the earth, in the trees, or 

 on the surface of the ground. For example, 

 whales were at first classified as fish be- 

 cause they lived in water and had a body 

 plan resembling fish, in spite of the fact that 



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