1861.] on the Metamorphoses of Insects. 377 



silkworm consumes, within thirty days, about 60,000 times its primi- 

 tive weight; one hundred worms, just hatched, weighing about one 

 grain. In their passage to the final winged state, a great difference is, 

 as might be expected, manifested in the size and condition of the 

 stomach. In the larva it occupies nearly the whole of the interior of 

 the body, but in the subsequent changes it becomes gradually reduced 

 to a very minute sac, a honey-stomach being developed, and becoming 

 proportionately extended in size. 



In the changes of insects there are two principal differences to be 

 observed ; some being active during their whole lives, without under- 

 going any deathlike or inactive state in their existence: whilst the 

 others pass through an inactive pupa state, in which latter the meta- 

 morphosis is said to be complete, the perfect insect being quite unlike 

 the earlier stages of its existence. 



Of the former class, the mole cricket was selected as one example, 

 and the habit of the female in burying its eggs in an oval cell in the 

 soil, and the adaptation of the fore-legs of the parent to the operation 

 of burrowing, were described. The larva has no wings ; but in its 

 general form and the structure of its legs it agrees with the perfect 

 insect. In the pupa state the rudiments of wings are developed in the 

 shape of scales upon the back, whilst in the perfect state the wings 

 are of large size, of the most delicate gauze-like texture, and which, 

 in order to protect them from injury underground, are capable of 

 being folded up into a fan-like mass, scarcely thicker than a large pin, 

 lying upon the back, thus forming no impediment to the subterranean 

 progress of the insect. The larva and pupa states of the dragon-fly, 

 and its aquatic predaceous habits, and the remarkable structure of its 

 mouth, were next described. 



Of the insects which undergo a deathlike pupa state, the common 

 cockchafer served as an example, the larvae of which make oval cells 

 in the ground, in which they are transformed to inactive pupae, with 

 the limbs lying upon the breast. The grubs acquire their full size 

 and undergo their pupa state at the spring season of the year, and are 

 turned up in hundreds in the tillage of the ground required at that 

 season, forming a great attraction to the rooks, which are to be seen 

 following the plough in search of them as it passes along, their young 

 being then newly hatched, and most ravenous in their demands for 

 food. Here, therefore, we have an exemplification of those " Har- 

 monies " which exist everywhere throughout nature. 



The ant-lion, with its funnel-shaped pit for trapping its prey — the 

 ichneumon fly, depositing its eggs in the bodies of other insects— rthe 

 humble-bee, with its pollen brushes and pollen baskets — the common 

 gnat, with its boat-like raft of eggs floating on the surface of the 

 water— the cheese-hopper, with its hooked jaws and its two catches at 

 its tail, by which it is able to concentrate the force for effecting its 

 spring, and the common flea, were then described in detail as to their 

 changes and habits, the whole being illustrated with large highly- 

 magnified figures. 



