DWELLINGS. 1 39 



these refuges permanently ; others only remain there 

 during the winter ; others, again, who live during the 

 rest of the year in the open air set up dwellings to 

 bring forth their young, or to lay their eggs and rear 

 the offspring. Whatever the object may be for which 

 these retreats are built, they constitute altogether 

 various manifestations of the same industry, and I 

 will class them, not according to the uses which they 

 are to serve, but according to the amount of art 

 displayed by the architect. 



In this series, as in those which we have already 

 studied, we shall find every stage from that of beings 

 provided for by nature, and endowed with a special 

 organ which secretes for them a shelter, up to those 

 who are constrained by necessity to seek in their own 

 intelligence an expedient to repair the forgetfulness 

 of nature. These productions, so different in their 

 origin, can only be compared from the point of view 

 ■ of the part they play ; there are analogies between 

 them but not the least homology. 



Animals naturally provided with dwellings. — Nearly 

 all the Mollusca are enveloped by a very hard cal- 

 careous case, secreted by their mantle: this shell, which 

 is a movable house, they bear about with them and 

 retire into at the slightest warning. 



Caterpillars which are about to be transformed into 

 chrysalides weave a cocoon, a very close dwelling in 

 which they can go through their metamorphosis far 

 from exterior troubles. It is an organic form of 

 dwelling, or produced by an organ. It is not necessary 

 to multiply examples of this kind ; they are extremely 

 numerous. In the same category must be ranged 

 the cells issuing from the wax -glands which supply 

 Bees with materials for their combs in which they 



