210 Silk Manufacture. 



him, as in order to their acquiring the necessary degree of skill, 

 they were sometimes allowed to act upon their own suggestions. 

 " But this signifies little," he would say, " compared to the ad- 

 vantage of diffusing and naturaUsing the improved art of rearing 

 silkworms by means of these pupils." Shortly after the publica- 

 tion of his treatise, large establishments were formed in Lombar- 

 dy, according to his recommendation: these were called Dando- 

 lieres^ as a testimony of respect for his disinterested philanthropy. 



' The causes which principally engender diseases in the silk- 

 worm, appear to exist in either damp, stagnate, or mephitic air. 

 Some experiments, tried in order to ascertain the fact, show, that 

 damp air is even more prejudicial to them, than mephitic (carbo- 

 nic acid) gas. If a silkworm be introduced into a receiver charg- 

 ed with ca.rbonic acid gas, and in which a bird would instantly die, 

 although the worm quickly exhibits signs of uneasiness and suffer- 

 ing, it will hve for ten, fifteen, or perhaps twenty minutes: no 

 warm-blooded animal could continue alive in such an atmosphere 

 for half that time. If, after remaining a few minutes, the worm 

 be withdrawn from the receiver, it will not exhibit any sign of in- 

 jury, but will be, apparently, as healthy as before inhaling this 

 pernicious gas. The silkworm appears endued with the power 

 to seize upon the minutest portion of vital air which may be held 

 by water, as it will live for some minutes immersed in this fluid, 

 particularly in its first ages; and, even when seemingly dead, it 

 will revive if taken out. It would seem, however, that when its 

 power of breathing is obstructed, the worm instantly dies: if, in- 

 stead of plunging it in carbonic acid gas, or in water, its eighteen 

 breathing holes are sealed up with grease, it expires instantane- 

 ously. 



' If a healthy silkworm be confined in a vessel, the air in which, 

 is charged with moisture, and heated to the temperature of 88° or 

 90", it will very soon exhibit symptoms of indisposition, and re- 

 ject food; the skin will slacken, the muscles soften, and contrac- 

 tion cease. In a short time evaporation will be obstructed, the 

 secretions indespensable to vitahty, which are effected in this an- 

 imal by means of contraction,* will be suspended, and ere long it 

 will perish. A warm-blooded animal, on the contrary, if suffi- 

 ciently supplied with pure air, can live without any suffering, and 

 perform all its functions without inconvenience, in such a temper- 

 ature, whatever be the attendant degree of moisture. This proves 

 how different is the structure of these two classes of animals. 



* The skin of the silkworm has so great a power of contraction, that 

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

 has been drawn out. 



