276 
THE ART OF REARING 
Thus great numbers of diseases will never ap- 
pear, if, — - 
1st. The silk-worms are kept thinly spread out 
on the wickers, that they may breathe and tran- 
spire freely. 
2nd. The; interior air of the laboratory is con- 
stantly and evenly maintained at the temperature 
I have recommended. 
3rd. When the air is never allowed to stagnate 
in the laboratory, and that it be kept in a gentle 
slow motion. 
4th. By constantly burning blazes when the ex- 
terior air is moist and stagnant, and the interior 
evaporation superabundant. 
5th. When the laboratory is kept light, light 
being the most powerful excitement to living 
nature. 
formed in the warm-blooded animals, when there is a sufficiency 
of vital air. Its organs are not apt to be relaxed so much as 
to impede nutrition and secretion. While the silk-worm, if 
the air is hot and damp, let there be ever so much of it, will 
pine, its skin will slacken, and the muscles soften, contrac- 
tion will cease ; in time, transpiration will be impeded. The 
indispensable secretions of life, which in this insect are effect- 
ed by means of contraction, are suspended. 
The skin which covers the worm, is of such contracting 
power, that wdiencut, it shrinks as if it had been drawn out, 
and was elastic. 
These reflections will exemplify how essential it is to re- 
novate the air, to dispel moisture in the laboratories, which is 
the greatest evil that can assail the silk-worms. 
