The reason why : $b a careful collection of many hundreds of reasons for things which, though generally believed, are imperfectly understood. A book of condensed scientific knowledge for the million — John Stuart Mill — John Shaqi
The reason why : $b a careful collection of many hundreds of reasons for things which, though generally believed, are imperfectly understood. A book of condensed scientific knowledge for the million
John Stuart Mill · en
(_Greatly magnified._)]
1315. _Why do they continually rise to the surface of the water?_
Because they require to breathe air, and therefore they come up to
the surface, where, elevating the tube (_b_) above the surface of the
water, they are enabled to breathe.
1316. _Why do some appear to have larger heads than others?_
Those that have apparently larger heads, and that breathe through tubes
attached to their heads (_d_) are in the _pupa_, or second stage of
development, and underneath the large shield by which their heads are
marked, their wings, feet, &c., are being formed.
[Verse: "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.
[Illustration: Fig. 82.--THE PERFECT GNAT. ESCAPING FROM THE PUPA-CASE.
_(Greatly magnified.)_]
This interesting metamorphosis may be seen going on in the summer
time, in every pond, brook, and reservoir. A fine sunny morning
calls up millions of these little boats from beneath the surface,
and the diver within that wonderful little bell breaks its sealed
doors, and flies away to enjoy the bright sunshine.
1319. _Why are beetles denominated "coleoptera?"_
Because they have wings protected by horny sheaths; the term
_coleoptera_ signifies _wings in a sheath_.
[Verse: "They shall lie down in the dust; and the worms shall cover
them."--JOB XXI.]
1320. _Why have beetles hard horny wing-cases?_
Because they live underground, or in holes excavated in wood, &c. If,
therefore, their wings were not protected by a hard and firm covering,
they would be constantly _liable to destruction_ from the movement of
the insect within hard and rough bodies.
[Illustration: Fig. 83.--STAG-BEETLE, SHOWING ITS WINGS UNFOLDED, AND
THE WING-CASES OPEN.]