CHAPTER 1 



Introduction 



A study of the form and structure of living things has a perennial interest, 

 not only for biologists but for everyone. It appeals to the aesthetic in us. 

 Philosophers have been concerned with it since the time of Plato, who 

 distinguished between matter and form and believed that spirit was 

 inherent in the latter. Most naturalists owe their first interest in animals 

 and plants to the almost infinite variety of forms which these display 

 and which make possible their identification. Although morphology 

 (Goethe's term), the science that deals with form, has lost the command- 

 ing position it once held, following the advent of physiology and the 

 disciplines that connect biology with the physical sciences, it still remains 

 the foundation for any thorough knowledge of living things. We must 

 all be morphologists before we can be biologists of any other sort. 



In a famous sentence Charles Darwin paid tribute to morphology by 

 calling it the very soul of natural history. How curious it is, he remarked, 

 that the hand of a man and of a mole, the leg of a horse, the paddle of 

 a porpoise, and the wing of a bat, despite the great difference in their 

 functions, should all be formed on the same basic pattern. Specific 

 bodily forms and structures had long been used to distinguish the major 

 groups of plants and animals and were also the basis of that "idealistic" 

 morphology which so intrigued Goethe and the biologists of his day. 

 Darwin, however, saw in the science of comparative morphology some- 

 thing far more significant— a strong support for the doctrine of evolution, 

 for only by assuming a common ancestry for each of the groups that show 

 a common pattern of bodily form could these similarities be explained. 

 Form was widely acknowledged as the most distinctive character on 

 which the phylogenetic relationships of organisms could be based and a 

 truly natural system of classification constructed. 



The study of organic form, however, poses a problem deeper still, and 

 one concerned with the very character of life itself. From the facts of 

 embryology it is evident that in the development of an individual there 

 occurs as regular a progression of changes in form as has taken place in 

 evolution. Indeed, the theory of recapitulation called attention to some 



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