410 NOTES ON THE SILK-PRODUCING INSECTS 



This analysis is remarkable from its great similarity to the composition 

 of glass manufactured at the present day. To take the analysis of window* 

 glass, by M. Dumas, cited in his work under number 4, we find : — 

 Silex ..... 68-65 

 Lime .... 9 - 65 



Soda . . . . . 17"70 



Aluminium .... 4-00 



100-00 



Perhaps in this analysis some traces of manganese and iron may have 

 been overlooked ; but with these exceptions, it is clear that both analyses 

 indicate an almost identical composition. The glass which M. Dumas 

 analysed was a specimen inferior to what is generally manufactured now. 

 Modern window-glass gives an average analysis of — 



Silex ..... 72-50 

 Lime . . . . 13-10 



Soda ..... 13-00 

 Aluminium . . . . 1-00 



Oxydes of iron and manganese . . 0-40 



100-00 



J. M. 



NOTES ON THE SILK-PRODUCING INSECTS OF INDIA AND ITS 

 ADJACENT COUNTRIES. 



BY FREDERIC MOORE, 

 Mem. Entom. Soc. Lond., Stettin, &c. 



1. Bombyx mori (Linn.). Syst. Nat. 1., p. 817 (1767). The common 

 Mulberry Silkworm. 



Habitat. Northern Provinces of China. Cultivated in China, Bengal, 

 Cashmere, Persia, Herat, Afghanistan, France, Spain, and Italy, in all 

 which countries it produces but one crop annually, spins the largest 

 cocoon and the best silk. Silk, pale yellow. Caterpillar feeds on the 

 mulberry. All who have attended to the rearing of silkworms, Captain 

 Hutton writes me, will doubtless have remarked that there are always a 

 number of dark grey worms among tbe pale cream coloured batch ; 

 noticing this, it struck me there must be some reason for it, and I thought 

 that either the species had at some remote period been crossed by another 

 and that nature was making an effort to separate them, or that the whole 

 stock had originally been dark and become changed by a long course of 

 domestication. I, therefore, picked out the dark ones and fed them 

 separately, and when the moths came forth they were allowed to couple 



