. British insects : a familiar description of the form, structure, habits, and transformations of insects. uffice to say that in it are repre-sented nearly all the principal parts which exist in thehuman eye, even to the iris and pupil, although togetherthey form a long slender cone instead of a globe* (fig. 2). This striking dif-ference finds itsexplanation whenwe consider thatthis form, by re-ducing the raysof light which canpossibly reach theretina to suchonly as fall di-Eyes of Hive Bee (Male). ^.^^q^ upon it, pre- vents the confusion which would arise from the recep-tion by each eyelet of
. British insects : a familiar description of the form, structure, habits, and transformations of insects. uffice to say that in it are repre-sented nearly all the principal parts which exist in thehuman eye, even to the iris and pupil, although togetherthey form a long slender cone instead of a globe* (fig. 2). This striking dif-ference finds itsexplanation whenwe consider thatthis form, by re-ducing the raysof light which canpossibly reach theretina to suchonly as fall di-Eyes of Hive Bee (Male). ^.^^q^ upon it, pre- vents the confusion which would arise from the recep-tion by each eyelet of images from all sides. It may beobserved here that some insects ( the butterfly)possess as many as 34,650 of these eyelets. Very curious observations have been made upon theconnexion which exists between the size and position ofthe eyes, and the flight of the insect. Thus the dragon-flies and butterflies, alike remarkable for the freedomand extent of their flight, have large and convex eyes,so placed that the field of vision must be very again, as the bees, which have long and narrow. * In this figure (partly borrowed from Dr. Carpenter) the lenses aremade large out of proportion, in order the better to show their form. EXTERNAL STRUCTURE OF INSECTS. 27 eyes, with upward and downward but little lateral scope,have an irregular flight, usually directed up, down, or for-ward, but very little from side to side. The field ofvision of the grasshoppers, &c., is still more limited, andtheir flight is short and hesitating. In the earwigs, whichfly little and crawl much, the eyes are small, and areplaced on the top of their flat heads. It has also been observed that in the eyes of someinsects (as the dragonfly) the eyelets are by no meansuniform in size, the surfaces of the upper being con-siderably larger than those of the lower eyelets. Theinference from this appears to be, that there is somevariation in the length of the» sight—the eyelets turnedearthwards being p
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Keywords: ., bookauthorme, bookcentury1800, bookdecade1870, booksubjectinsects
