SILK-WORMS. 
133 
near its legs, and which are called stigmata. 
(Chap. II.) These breathing vessels are almost 
all stopped up, and covered when the worms are 
heaped together, which makes their breathing 
difficult, and the transpiration also ceases, much 
to the detriment of the insect. (Chap. XII.) 
If these causes of disease are not well ascer- 
tained, and rectified as soon as they appear, we 
shall find, when we were in hopes of gathering an 
abundance of silk, that the whole crop is de- 
stroyed ; and of this, unfortunately, we have very 
frequent example in all countries, and in all cli- 
mates. 
It is, therefore, very important to know accu- 
rately all the symptoms of disease in silk-worms, 
and when they are discovered, to be able to treat 
them ; although I can nearly engage that no 
disease will appear, if the silk-Avorms are ma- 
naged according to my directions for the fifth 
age. 
In this chapter I shall speak — 
1 . Of the hygrometer or barometer, the instru- 
ment with which the degrees of moisture of the 
air may be measured in the laboratory. 
2. Of the bottle for purifying the air, and for 
drying the excremental matter deposited on the 
wicker hurdle. 
digression which is foreign to my object, and which can only 
prove interesting to medical men. — Translator. 
