"Because thy loving kindness is better than life, my lips shall praise thee."—Psalm lxiii.
1317. Why, when the water is disturbed, do the larvæ descend more rapidly than the pupæ?
Because the pupæ are in a torpid condition, awaiting the formation of their perfect organs.
1318. Why are the flies able to escape from the water?
Because, as their formation becomes perfected, and the fluids of the body of the pupa become absorbed in the production of the light texture of the wings, &c., the body and its case become lighter than the water, and rise and float upon the surface. The pupa-case then forms a natural boat, from which the fly emerges, and spreading its wings, enters upon the final state of its existence.
Fig. 82.—THE PERFECT GNAT. ESCAPING FROM THE PUPA-CASE.
(Greatly magnified.)