296 
THE ART OF REARING 
and of augmentation or diminution of tempera- 
ture in the laboratory*. 
Let us now examine a moderate-sized labora- 
* Since the publication of this work, there have been 
irected large laboratories in Lombardy, which are called 
Dandolieres, an honourable testimony to the philanthro- 
pical Parmentier of Italy. Some have offered favourable 
results ; however, some proprietors were disappointed, and 
the utility of the laboratories has been called in question. 
Divers objections were started, which I shall state, with 
the answers which were given by M. Dandolo. 
It is said that when a disease appears in the great labora- 
tories, it is propagated with greater facility ; and that all 
the silk-worms then inevitably perish, which would not occur 
were they divided into smaller and separate apartments. 
M. Dandolo first remarks that there exist no contagious 
disorders among silk-worms, and if all the silk-worms of a 
great laboratory die successively, it must be solely owiDg to 
some incipient cause, which killed the first, and which con- 
tinues to act on them all as long as it remains unremoved. 
“Is it not well known that several palpable causes may 
strike a number of men, such as bad air, corrupt water, 
unwholesome food, and that as long as these causes are not 
removed, without being contagious in the least degree, 
these vitiated causes will continue to commit general ra- 
vages ? A number of facts have long ago proved, and par- 
ticularly in 1816, that all the silk-worms of a whole pro- 
vince may die, although reared in small separate laboratories. 
The mortality in large or small laboratories depends always 
and entirely upon the management of the establishment and 
the regularity of it. The only difference will be this : that 
an ignorant cultivator will only lose the small number of 
silk-worms in a small laboratory ; whereas if the director of 
a large laboratory be equally ignorant, he will of course lose 
twenty, thirty times as many worms, in proportion to the 
size of the establishment and his own ignorance. This is 
