LEPIDOPTERA. 



235 



Commerce recognises two kinds of white silk : theyfrj-/ white and 

 the second white. The silk of the first white is produced by the race 

 Sina, the cocoons of which are of a perfect and azured white. They 

 produce the most beautiful and most precious silk, and serve for the 

 fabrication of light and delicate-coloured tissues. The silk of the secotid 

 white is furnished by two races : the Espagnolet and the Roquemaiire. 



The races that produce yellow cocoons are more numerous than 

 the white ones. The yellow races are divided into three groups : 



"^w^y 



Fig. 214. — Spherical cocoon 

 of the Bombyx mori. 



Fig. 215. — Cocoon of Bombyx mori, 

 drawn in towards the middle. 



those that have small, middle-sized, or large cocoons. The first and 

 second are stronger, and more esteemed than the last. 



The greater number of the races of silkworms have, let us here 

 mention, white and yellow cocoons ; there are some, however, whose 

 cocoons are of a greenish white, or even quite green, or of a reddish 

 green. One race, raised in Tu-scany, near Pistoja, has cocoons of a 

 pale rose colour ; and, lastly, mention has been made of cocoons of 

 a purple colour. 



When the cocoons are completed, the people in charge of the 

 rearing- establishments separate them from the heather and sell them 

 to the silk-spinners. But they must manage to get these cocoons 

 into a state in which they will remain entire during a long time. They 

 must, in other words, kill the chrysalis, to prevent the cocoons being 

 pierced by the moth. To kill the chrysalis so as to prevent the 



