ENTOMOLOGY. 
83 
meats of munducation are strong and efficient; the 
digestive organs greatly developed, and the skin perio- 
dically thrown off to remove any impediment to the 
distention of the body. The consumption of food is 
necessarily great, in some cases exceeding that of 
any other animals, regard being had to their respec- 
tive size. In fact, many of the kinds which consume 
the foliage of plants eat with little intermission ; and, 
in some instances, they continue to feed both by night 
and day. The growth of the larvae of flesh-flies 
( Sarcophaga ) is unusually rapid, some of them having 
been found to become 200 times heavier in twenty- 
four hours. When it has attained its full growth, 
the caterpillar of the goat moth is sometimes 72,000 
times heavier than when newly hatched. The ex- 
periments of Count Dandalo on the silk-worm, make 
it appear that when just hatched, this caterpillar is a 
line in length, and a hundred weigh about a grain ; 
after the first moulting, the length of each is four 
lines, and a hundred weigh fifteen grains ; after second 
moulting, length 6 lines, weight 94 grains ; after third 
moulting, length 12, weight 400 ; after fourth moult- 
ing, length 20, weight 1628; after fifth moulting, 
the length of each is upwards of three inches, and a 
hundred weigh about 9500 grains. 
The number of these moultings or changes of skin 
varies greatly in different insects, but it is always alike 
in the same species. The intervening periods like- 
wise vary, being dependent on the length of life 
allotted to the larvee. In the silk worm, as has just 
been seen, the moultings are five, and all these occur 
