OBGANIZATION OF ANIMALS. 189 



but they have remarkable analogies, being all organized 

 for flight, by having expansions of the integuments ex- 

 tended, on fingers prolonged for this purpose. Indeed, in 

 contemplating and comparing with each other different zoolo- 

 gical groups, it would seem as if nature's tendency was 

 to cause each type to pass through a series of analogous 

 modifications. Thus amongst insects, spiders, and Crustacea 

 we observe the general plan of the organization modified 

 in the same way, according as the animal is intended to live 

 on solid food, or as a parasite by sucking the juices of another 

 being. 



356. Organic Harmonies. In the midst of the innu- 

 merable variety in form and structure which the animal world 

 presents, may be observed a certain general harmony which 

 seems to regulate all the parts of this vast creation ; and this 

 principle of co-ordination is all the more remarkable if we 

 restrict our observation to the entire of the structures com- 

 posing a single animal. Between every part there reigns the 

 strictest mutual dependence, so as to forbid all idea of chance 

 in its construction ; all are in the strictest accord. Some of 

 these harmonies are so obvious and striking that the natu- 

 ralist may, from the observation of a single organ a tooth 

 for example, deduce nearly the whole natural history of the 

 animal. From the subjoined figure (Fig. 131) 

 may readily be inferred that the animal had 

 a skeleton, a cerebro-spinal axis, nerves, 

 Ac.; in short, that it was a hot-blooded 

 mammal, and that it lived on flesh. In 

 fact, from this single organ may be deduced 

 nearly the whole structure of this carni- 

 vorous mammal, a priori, or without hav- 

 ing ever seen it. Proceeding on these 

 principles of organic harmonies, the true 

 nature of the fossil organic world was first 

 discovered by Cuvier ; he it was who first the Lion, 

 applied these laws to fossils, and by these 

 means effected the restoration of an organic world long since 

 extinct. 



357. In studying this law of organic harmony, we 

 soon discover another, the subordination of characters. It 

 becomes evident that all parts of the animal economy have 

 not the same importance ; that certain organs may undergo 



