THE CABBAGE-CATERPILLAR 31 1 



single opening and is soon wriggling about, perched on 

 the surface of the caterpillar. The lens cannot perceive 

 the hole, which closes on the instant. There is not even 

 a haemorrhage: the bottle has been drained too thor- 

 oughly. You must press it between your fingers to 

 squeeze out a few drops of moisture and thus discover 

 the place of exit. 



Around the caterpillar, who is not always quite dead 

 and who sometimes even goes on weaving his carpet 

 a moment longer, the vermin at once begin work at 

 their cocoons. The straw-colored thread, drawn from 

 the silk-glands by a backward jerk of the head, is first 

 fixed to the white network of the caterpillar and then 

 produces adjacent warp-beams, so that, by mutual en- 

 tanglements, the individual works are welded together 

 and form an agglomeration in which each of the grubs 

 has its own cabin. For the moment, w'hat is woven is 

 not the real cocoon, but a general scaffolding which will 

 facilitate the construction of the separate shells. All 

 these frames rest upon those adjoining and, mixing up 

 their threads, become a common edifice wherein each 

 grub contrives a shelter for itself. Here at last the ' 

 real cocoon is spun, a pretty little piece of closely woven 

 work. 



In my rearing- jars I obtain as many groups of these 

 tiny shells as my future experiments can wish for. 

 Three-fourths of the caterpillars have supplied me with 

 them, so ruthless has been the toll of the spring births. 

 I lodge these groups, one by one, in separate glass tubes, 

 thus forming a collection on which I can draw at will, 



