OF INSECTS. 165 



may without impropriety be noticed in this place. 

 It consists of a reticulated web, of a white or yellow 

 colour, the shreds of which, when examined by the 

 microscope, are found to be constituted by small 

 globules of animal matter. It is more or less com- 

 pact in different insects, and even in the same insect 

 according to its age, being loosest and most stringy 

 in young individuals. It very nearly corresponds to 

 the fat of the larger animals, but as chemical analysis 

 has produced different results, its essential properties 

 and uses cannot be considered always the same. 

 Virtually, however, its uses may be regarded as two- 

 fold ; first, to protect the various organs by forming 

 a soft and elastic bed, which retains them in their 

 place, and prevents them coming in too close con- 

 tact with each other ; secondly, to afford a certain 

 degree of nutriment when the insect is not in a con- 

 dition to receive food. In the latter case, it exactly 

 corresponds to the store of fat found in hybernating 

 mammalia, when they go into their winter quarters. 

 It is particularly plentiful in the caterpillars of the 

 Lepidoptera ; as they go through their various meta- 

 morphoses it gradually becomes more scanty, till it 

 almost entirely disappears in the mature fly. It is 

 hence naturally inferred that it supplies the requisite 

 nutriment during the pupal sleep, and is gradually 

 absorbed to aid in the development of the newly 

 formed parts. Next to caterpillars it is most abund- 

 ant in Coleoptera, Orthoptera, Hemiptera, and Neu- 

 roptera ; or, speaking generally, it is more plenti- 

 ful in masticating than sucking insects. Some dis- 



