SILK-WORMS. 
31 
cultivator has sought those mulberry trees only 
which produce the largest leaves, and those of most 
known in Italy.) 10th, Morus tinctoria. 1 1th, Morns pa- 
pyrifera (these two latter species have been recently trans- 
ported into another class of plants, and termed Broussone- 
tia, from the name of M. Augustus Broussonet, a distin- 
guished professor.) The list I have given sufficiently shews 
the varieties of mulberry leaves which might be found even 
more suitable to the nourishment of the silk-worm, than those 
hitherto used. 
The ditference existing among the leaves of the grafted 
plants is much less perceptible than the difference in the va- 
rieties of wild leaves. Thus, a wild mulberry tree of ten 
years’ growth, of the broad-leaved species, unindented, will 
produce a greater weight of leaves than five trees of the same 
age, of the much indented leaf species. 
The following is the result of my experiments upon the 
leaves of the grafted mulberry tree : 
1. One hundred ounces of leaves nearly ripe, picked in the 
same day from a Tuscany mulberry tree, produced thirty 
ounces, after dessication. 
2. One hundred ounces of the leaves of the giazzola mul- 
berry tree produced thirty-one ounces and a half. 
3. One hundred ounces of the double-leaved mulberry tree 
produced thirty-six ounces. 
This variety of the species produces more fruit than any of 
the others. 
All these leaves diminish still less in their weight, when they 
are perfectly mature. There are few ripe leaves of different 
trees which contain so little liquid as those of the mulberry 
tree when ripe ; while, on the contrary, the young leaf of the 
mulberry contains much liquid. 
A hundred ounces of the young leaves, such as are given 
to the silk-worm, in the first stage, weigh less than twenty- 
one ounces when dried ; thus, it is evident, they contain al- 
most four-fifths of water. This abundance of liquid pro- 
C 4 
