SILK-WORMS. 
23 
They have admitted in Persia, upon an econo- 
mical principle, the custom of feeding the silk- 
worm upon the boughs of the mulberry-tree, and 
not upon the leaf alone, as we practise it, and as 
it is the custom in all the temperate regions. 
In this manner the leaves adhering to the branch 
are fresher and have a better flavour, and are, 
consequently better calculated for nutrition ; the 
silk-worm thus eating them entirely, by these 
means there is no waste. In those climates they 
prune the small branches twice a year, because 
the summer being longer, the mulberry-tree is 
more vigorous there than it is with us. 
Here, on the contrary, the mulberry-tree can- 
not even bear the stripping of its foliage once a 
year without being injured, and certainly would 
die if stripped twice. 
All things considered, I am well persuaded that 
one of our good crops will be equal in produce to 
any crops that may be gathered elsewhere in a year. 
The cocoon of the silk-wonn is commonly 
white, straw colour, or deep yellow ; we see but 
few here of a greenish hue, or, indeed, of any 
other colour. The black, and the tiger-spotted 
silk-worm, in general, produce cocoons of the 
same colour as other silk-worms. 
The silk-worm is of the class of caterpillars that 
have the greatest number of legs ; it has sixteen, 
that is to 6ay, six shelly or scaly legs, and ten 
