196 PHIPSON, ON THE UTILIZATION OF MINUTE LIFE, 
domestication, are—1. Silk-producing insects—treated of in 
Chapter II. Many curious and interesting facts concerning 
this useful class of insects will here be found; and amongst 
these one which strongly exemplifies the enormous voracity 
and capability of assimilation and consequent rapid growth 
to which animal organisms may attain, and which may be 
nearly said to equal what is witnessed among some of the 
fungi, whose growth can almost be seen : 
“ The larve born from one ounce of eggs require during their first age, 
which lasts five days, about 7 lbs. weight “of mulberry leaves. After the 
first moulting, and during the second age, which lasts only four days, they 
require 21 Ibs. of leaf, During the third stage, which lasts a week, they 
devour 70 Ibs. of mulberry leaf; in the fourth stage (also a week), 
210lbs.; and during the fifth stage, from 1200 to 1300 lbs. of leaf. On 
the sixth day of this last period, they devour as much as 200 lbs. weight 
of leaf, with a noise resembling the fall of a heavy shower of rain. On 
the tenth day they cease eating, and are about to undergo their first 
metamorphosis.” 
Another curious and important circumstance here noticed 
is the apparent success that has attended the endeavours 
to improve the breed of the common silkworm (Bombyx mori) 
by M. André Jean, of Neuilly. This gentleman has proceeded 
upon the principle of selection so extensively adopted in the 
breeding of other animals of larger growth. And he has thus 
been very successful in creating a valuable race of silkworms, 
simply by causing the largest and finest male and female 
moths to breed together. ‘The larve developed from these 
eggs are of very large size when compared with the common 
silkworm. 
He next speaks of colour-producing imsects—of insects pro- 
ducing wax, resin, honey, manna, &c. With reference to the 
latter substance, or rather to the various substances included 
under the term, although he mentions the production of an 
edible manna from the Eucalyptus resinifera, he omits to notice 
that it is, in fact, the produce of an insect ; of which an account 
will be found in the fifth volumeof this Journal, underthe head of 
“Laap or Lerp.” The substance so termed is one highly worthy 
of the attentionof chemists, more especially as it seems to afford 
an instance of the occurrence of a substance similar to that of 
which starch-grains are composed, but which is amorphous, 
and produced, as it would appear, in a semifluid form by an 
insect which spins it into a beautiful. conical habitation, 
presenting, under the microscope, very much the appearance of 
a Chantilly basket composed of spun sugar. 
Then we have an account of insects employed i in medicine, 
food, &e. Amongst the latter are some which, in any case, 
show to what extremities necessity will compel mankind. 
