XIII 



ADVANTAGES OF BEING A VERTEBRATE 



Preview. Vertebrate cliaracteristics • Skeletons • Invertebrate attempts • 

 The vertebrate endoskeleton • Suggested readings. 



PREVIEW 



How fortunate it is that we are vertebrates, not only vertebrates 

 in general but mammalian vertebrates of the royal primate line which 

 has blossomed finally into human beings ! 



When one thinks over the myriads of lowly, less endowed animals 

 scattered along the devious highways of evolution, who might have 

 been our near relatives, it is a real privilege to claim relationship 

 with such highly endowed primates as monkeys and apes. With 

 the inclusive vertebrate type, to say nothing of the specialized Pri- 

 mates, there are certain outstanding structures and qualities which 

 we as mankind are thankful to possess. They are so famihar to us, 

 however, that we are apt to forget how far our fortunate biological 

 heritage is dependent upon them. 



Only a few of these distinctive vertebrate characteristics that give 

 us occasion for self-congratulation may be pointed out here. A 

 consideration of the Vertebrates as such forms a biological science 

 in itself, set forth in a voluminous Hbrary of descriptive and inter- 

 pretative books. 



Vertebrate Characteristics 



Even a partial list of the distinctive vertebrate endowments 

 would include the following: 1, a highly developed nervous system, 

 based upon a hollow dorsally-located nerve cord ; 2, a unique embry- 

 onic skeletal axis, called the notochord, which is the foundation for a 

 living internal skeleton, adaptable to the changing demands of growth ; 

 3, a peculiar kind of blood, that in the higher forms makes the mainte- 

 nance of a constant body temperature possible regardless of the sur- 

 rounding temperature ; 4, various devices for effectually transporting 

 the blood to every part of the body, devices that are as superior to the 

 methods employed by non-vertebrates as modern highways and 

 means of transportation are better than the conditions encountered 

 in the days of the trackless wilderness ; and 5, locomotor organs for 



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