12 



leaves of the mulberry tree (Plate XL.) The moth 

 (Plate I., Figs. 1 and 2) is therefore named Bombyx mori. 

 It must not be inferred, however, that there is only one 

 species, as is too generally thought. Mr. F. Moore assures 

 me there is sufficient structural variation in moths which 

 were at one time understood to be Bombyx mori to 

 constitute a specific difference. The following species feed 

 on the mulberry, ana their silk is in ordinary and pro- 

 miscuous use along with that of the mori : — 



Bombyx sinensis (Hutton), 



Bombyx crcesi (Hutton), 



Bombyx fortunatus (Hutton), 



Bombyx arracanensis (Hutton), 



Bombyx textor (Hutton), 

 and no doubt several others not yet defined, but whose 

 silk varies vary much, such as that called Canton and that 

 called Tsatlee, although both are from China, as well as 

 the silk from Japan, which has a thicker fibre than the 

 mori silk of other countries, being 16 1 50 of an inch thick, 

 as against y^Vo °^ an ^ ncn °f ^ ne wor ^ S1 ^ 0I> Italy. The 

 strength and tension of this and the wild silks, as well as 

 the respective sizes of their cocoons, are given in my table 

 of microscopic measurements on page 68, which I have 

 carefully revised. I commend the study of this table to all 

 engaged in silk manufacturing, whether of ordinary or 

 wild silks, as I consider the results of the highest impor- 

 tance. In the column of relative strengths it will be seen 

 that the breaking strength of a single fibre of Bombyx 

 mori or mulberry-fed silk is 2| drams, whilst the weight 

 of 7 drams is required to break a single fibre of Tusser 

 silk. 



The eggs of Bombyx mori and the other species of Bombyx 

 form a most important article of commerce between Japan 

 and Europe. They are imported from Japan into Italy 

 and the South of France annually, to supply the deficiency 

 caused by the silkworm disease known as pebrine, and also 

 to infuse, as it were, new blood. The value of the eggs is 

 about 25s. per oz.. Twelve pounds of cocoons are required 

 to produce one pound of silk. The value of the raw silk 

 of Bengal in London is now from 14s. to 18s. per lb. 

 The colour is generally of a rich golden yellow ; but it is 

 also sometimes white. In China and Japan it is all white, 

 with rare exceptions. 



