File:Structure and classification of insects (1872) (14760250596).jpg

Identifier: structureclassif00ebel (find matches)
Title: Structure and classification of insects
Year: 1872 (1870s)
Authors: Ebell, Adrian John, 1840-1877
Subjects: Insects Insects
Publisher: New York : Ebell
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

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er^ situation^ figure^ clotJmig^ color andsize. The compound eye, when seen under the miscroscope,displays a great number of convex, six-sided pieces;each of these is a distinct lens and has on the inner sideof it a cone-shaped retina at the very point or apex ofwhich alone is the optic nerve, or nerve of sight. Thesecones are often beautifully colored and placed side byside as the lobes of a section of an orange. The number of these lenses varies from about 50 toover 30,000. Hooke computed those in the eye of a horse-fly toamount to nearly V,000; Leeuwencock found more than12,000 in that of a dragon-fly; and 17,325 havebeen counted in that of a butterfly, and, according to 44 THE HEAD. Geoffroy,in some butterflies there are no fewer tlian 84,650.And we are informed still further by other writers thatin some beetles these lenses are smaller and even morenumerous. The remaining points of study in relation tothe eyes of insects will have to be left for the investiga-tion of the student.
Text Appearing After Image:
Antennje. Filiform.Capitate.Perfoliate Club.Geniculate. Lamellate.Fissate Club.Serrate.Pectinate. THE HEAD. 45 The Antennii6 appear to be among the most import-ant of all the organs of the adult insect, and of a greatvariety of forms and uses. They are filaments or feelers attached to the upperpart of the head which not only aid and guide the insectin its motions, but which also probably serve as theorgans of several of the special senses, as feeling, hearing,and smell. They may be observed in relation to their member^insertion substance^ situation, proportion, general formand structure, clothing, expansion, motions, and state ofrepose, and uses or functions. Insects invariably have but two antennae, while someof the lower articulates, as the Crustaceans, have four. With the aid of an ordinary magnifying glass—oreven indeed, in most insects, without any such assistance,the student may observe the details mentioned above,such as form, structure, clothing, or covering, &c., witha

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