56 THE WONDERS OF INSTINCT 



various stages of the metamorphoses. It is not there: 

 I find not the least trace of murexide. The lid, therefore, 

 is composed solely of carbonate of lime and of an organic 

 cement, no doubt of an albuminous character, which gives 

 consistency to the chalky paste. 



Had circumstances served me better, I should have 

 tried to discover in which of the worm's organs the stony 

 deposit dwells. I am however, convinced : it is the 

 stomach, the chylific ventricle, that supplies the chalk. 

 It keeps it separated from the food, either as original 

 matter or as a derivative of the ammonium urate; it 

 purges it of all foreign bodies, when the larval period 

 comes to an end, and holds it in reserve until the time 

 comes to disgorge it. This freestone factory causes me 

 no astonishment: when the manufacturer undergoes his 

 change, it serves for various chemical works. Certain 

 Oil-beetles, such as the Sitaris, locate in it the urate of 

 ammonia, the refuse of the transformed organism; the 

 Sphex, the Pelopaei, the Scoliae use it to manufacture the 

 shellac wherewith the silk of the cocoon is varnished. 

 Further investigations will only swell the aggregate of 

 the products of this obliging organ. 



When the exit-way is prepared and the cell uphol- 

 stered in velvet and closed with a three-fold barricade, 

 the industrious worm has concluded its task. It lays 

 aside its tools, sheds its skin and becomes a nymph, a 

 pupa, weakness personified, in swaddling-clothes, on a 

 soft couch. The head is always turned towards the door. 

 This is a trifling detail in appearance; but it is every- 

 thing in reality. To lie this way or that in the long cell 



