io8 INSECT LIFE 



VIII 



precisely like that of the preceding purse, the inner 

 one, the third of the cocoon, is a kind of lacquer — a 

 brilliant violet-brown varnish, fragile, very soft to 

 the touch, and of quite a different nature to the rest 

 of the cocoon. The microscope shows that instead 

 of being a felt of silky filaments like the other 

 coverings, it is a homogeneous covering of a 

 peculiar varnish, whose origin is, as we shall see, 

 sufficiently strange. As for the resistance of the 

 conical end of the cocoon, one finds it caused by a 

 load of friable matter, dark violet, and shining with 

 numerous black particles. This load is the dry mass 

 of excrement, ejected once for all by the larva, 

 inside its cocoon, and to it is due the darker colour 

 of the conical end. The average length of this 

 complex dwelling is twenty -seven millimetres, and 

 its greatest width nine. 



Let us return to the purple varnish which covers 

 the interior of the cocoon. At first, I thought it 

 should be attributed to the silk glands, which, after 

 serving to spin the double wrapper of silk and 

 the scaffolding, must finally have secreted it. To 

 convince myself, I opened larvae which had just 

 completed their task of weaving, and had not yet 

 begun to lay on the lacquer. At that period I 

 found no trace of violet fluid in their glands. It is 

 only seen in the digestive canal, which is swelled 

 with a purple pulp, and later in the stercorous load 

 sent down to the lower end of the cocoon. Else- 

 where all is white, or faintly tinged with yellow. I 

 am far from suggesting that the larva plasters 

 its cocoon with excrement, yet I am convinced that 

 this wash is produced by the digestive organs, and I 



