lO THE INDUSTRIES OF ANIMALS. 



dig out dwellings in the earth; even to-day there are 

 regions where Man does not act otherwise, preparing 

 himself a lodging by excavations in the chalk or the 

 tufa. Woven dwellings, constructed with materials 

 entangled in one another, like the nests of birds, 

 proceed from the same method of manufacture as the 

 woollen stuffs of which nomad tribes make their tents. 

 The Termites who construct vast dwellings of clay, 

 the Beavers who build huts of wood and of mud, have 

 in this industry reached the same point as Man. 

 They do not build so well, no doubt, nor in so 

 complex a fashion as modern architects and engineers, 

 but they work in the same way. All these ingenious 

 artisans operate without organs specially adapted to 

 accomplish the effect which they reach. It is with 

 such genuine industries that we have to deal, for the 

 most part neglecting other productions, more mar- 

 vellous in certain ways, which are formed by particular 

 organs, or are elaborated within the organism, and 

 are not the result of the intelligent effort of the 

 individual. To this category belong the threads 

 which the Spider stretches, and the cocoon with 

 which the Caterpillar surrounds himself to shelter his 

 metamorphosis. 



Intelligence and instinct. — By attentive observation 

 it is possible to find in animals all the intermediate 

 stages between a deliberate reflective action and an 

 act that has become instinctive and so inveterate to 

 the species that it has re-acted on its body, and thus 

 profoundly modified it so as to produce a new organ 

 in such a way that the phenomena are accomplished 

 as a simple function of vegetative life, in the same 

 way as respiration or digestion. 



If an individual is led to reproduce often the same 



