526 THE POPULAR SCIENCE MONTHLY. 



dependence, one upon another, and provoke morphological variations 

 which wholly change the aspect of each one of them. " The probosces 

 of bees and of butterflies would be useless to them if there existed no 

 flowers." The teeth of mammals tell what their regimen is. All their 

 structure is likewise derived and by a kind of reaction from it. " The 

 tongue of the ant-bear and its enormous salivary glands can evidently 

 be useful only for the capture of ants, termites, and other insects liv- 

 ing in societies. There are insects that never come out of the ant- 

 hills ; some of them are blind, and others can not eat anything but 

 the food with which the ants gorge them." Innumerable parasites 

 have been modified in a similar manner by the animal environment 

 accidentally chosen by them ; and all, starting from very different 

 points, have, under the empire of analogous conditions of existence, 

 put on similar characters. It is Darwin's glory to have established 

 that while the physical and organic mediums are incessantly changing 

 and endlessly producing the most varied and most unforeseen condi- 

 tions, there are none among them to which organisms have not been 

 able to bend themselves with a flexibility almost without limits. 



These relations of the being with its medium furnished " the most 

 powerful arguments for the doctrine of final causes. For this doc- 

 trine will hereafter be substituted a higher, a broader philosophy, a 

 conception of the living world which will be wonderful only by its 

 majestic simplicity. Every adaptation of a living being to a deter- 

 mined mode of existence has become no longer only a marvel to ad- 

 mire, but is also a problem to be resolved. This study, in fact, is 

 that of the whole of natural history." 



At this point is given a brilliant picture, in which, reviewing the 

 great divisions of the animal kingdom, the author designates in each 

 of the dominant forms of living beings the effect of the conditions of 

 their existence. Every type, we may say, is thus formed by these con- 

 ditions. To them must be attributed not only the variations in detail 

 which only are commonly called adaptations, but the essential traits of 

 the type, " due also to an anterior adaptation, the effects of which 

 have been transmitted from more or less remote ancestors to their jjos- 

 terity." It results from this that the characteristics proceeding from 

 the most ancient adaptations should be and are the most widely spread. 

 And, as it is precisely the degree of generality of a characteristic 

 which gives it its methodical value (the most general have been called 

 dominant by Cuvier), their order of subordination is simply their 

 order of antiquity. "The classifications, of which the dryness was 

 formerly legendary, thus become all-palpitating with historical inter- 

 est," for they relate to us the series of conditions of which the animal 

 kingdom is the work and the witness. 



Must man be excepted from the general operation of these laws ? 

 In no way. It is from the natural sciences thus renovated that we 

 must demand, says M. Perrier, " an exact and scientific notion of the 



