DISEASES OF SILKWORMS. 147 



soften, and contraction cease. In a short time 

 k vaporation will be obstructed, the secretions in- 

 lispensable to vitality, which are effected in this 

 inimal by means of contraction,* will be suspended, 

 nd erelong it will perish. A warm-blooded ani- 

 nal, on the contrary, if sufficiently supplied with 

 >ure air, can live without any suffering, and per- 

 orm all its functions without inconvenience, in such 



temperature, whatever be the attendant degree 

 f moisture. This proves how different is the 

 tructure of these two classes of animals." 



Silkworms are said to be extremely sensible of 

 ertain odours, and to be easily affected by them, 

 'obacco has been ascertained to be a deadly poison to 

 ilkworins. If a few grains of snuff is thrown on them, 

 mmediate pain seems to be felt, from the writhing 



the animal ; in about a minute convulsions will 

 nsue, and death speedily follows. Before the cat- 

 rpillar expires, it ejects from its mouth a watery 

 quid ; and should another larvae be touched with 

 lis fluid, it is certain to prove fatal. 



There is a disease to which silkworms are very 

 able in the south of France, which is called the 

 aundice, from the yellow colour exhibited by the 

 nimal while labouring under the malady. This 



* The skin of the silkworm has so great a power of contrac- 

 on, that, on being cut through, it shrinks in the manner of an 

 elastic substance that has been drawn out. 



