236 ORGANISMS ILLUSTRATING BIOLOGICAL PRINCIPLES 



The fact that the vertebrate skeleton is inside the body makes it 

 a changeable living structure which, by reason of its capacity for 

 continuous growth, keeps pace with the increasing demands of the 

 enlarging organism. With the introduction of such a scheme of 

 mechanical support, the ban upon size imposed by a lifeless exoskele- 

 ton is lifted, so that during the Age of Mesozoic monsters there were 

 dinosaurs and similar beasts, for example, that were able to lift tons 

 of flesh into the air upon majestic bony scaffoldings. These prehis- 

 toric giants proved impracticably large, however, and vanished 

 forever from the face of the earth after recording by means of their 

 fossil remains the results of these colossal experiments in the mech- 

 anism of living inside skeletons. There still remain today, elephants 

 on land and whales in water as living illustrations of how far it is 

 possible to go in the matter of size when an adequate living internal 

 support is provided. 



The remarkable superiority of the vertebrate endoskeleton over 

 all other skeletal devices is evident. It would be possible to go much 

 further and to unfold some of the marvelous details of adaptation 

 which every separate part of the vertebrate skeleton presents. That 

 would call for many pages. It is the task of the comparative anatomist 

 to assemble and elucidate the innumerable facts about the vertebrate 

 plan of structure, of which those involved in the skeleton are a 

 sample, and to point out wherein we are fortunate to be constructed 

 as we are. This is a fertile field, inviting intellectual adventure for 

 those who have the curiosity to explore it. 



SUGGESTED READINGS 



Adams, L. A., An Introduction to the Vertebrates, John Wiley & Sons, Inc., 



1933. 



A fine text. 

 Keith, Sir A., The Engines of the Human Body, J. B. Lippincott Co., 1919. 



Parallels intriguingly worked out for the mechanically minded. 

 Neal, H. V., and Rand, H. W. Comparative Anatomy, P. Blakiston's Son 



and Co., 1936. 



Written by two masters of the subject. 

 Newman, H. H., Vertebrate Zoology, The Macmillan Co., 1920. 



Just what the title indicates. 

 Walter, H. E., Biology of the Vertebrates, The Macmillan Co., 1928. 



Many illustrations. Bibliography. 

 Wilder, H. H., History of the Human Body, Henry Holt & Co., 1923. 



Told with literary grace without sacrifice to accuracy. 



