Text-book of comparative anatomy . ich first forms as an ectodermal de-pression and later becomes constricted whole compound eye would accordingto this be a modified and differentiatedocellus, in which the epithelial cells of theposterior proximal wall of the eye-pitdifferentiate into retinophorse and pigmentcells, grouped together as ommatidia (as inthe middle eye of the Scorpion). Thehypodermis, further, which spreads overthe vesicular eye, instead of forming onecuticular lens, forms many such lenses,which as corneal facets correspond innumber and position with the ocel
Text-book of comparative anatomy . ich first forms as an ectodermal de-pression and later becomes constricted whole compound eye would accordingto this be a modified and differentiatedocellus, in which the epithelial cells of theposterior proximal wall of the eye-pitdifferentiate into retinophorse and pigmentcells, grouped together as ommatidia (as inthe middle eye of the Scorpion). Thehypodermis, further, which spreads overthe vesicular eye, instead of forming onecuticular lens, forms many such lenses,which as corneal facets correspond innumber and position with the ocelli themselves may also be comparedwith the similarly constructed visual organsin the Annelida and Mollusca which ariseas ectodermal invaginations. If this new view of the facet eye isestablished, if the so-called crystallinecones are not simply refractive bodies, butthe actual terminal apparatus of the opticnerve, sensitive to light, it would lead toconsiderable modification of the theory ofsight by means of the compound B. Auditory Organs. FIG. 329.—The structure of an omma-tidium (single eye) of the facet eye. .4,According to Pattens view. B, accordingto Grenadiers view, cl, Cuticular corneal 111 the most various parts of the iens ; hy, hypodermis cells of the cornealbodies of the Insecta peculiar nerve lenses; r, retinophora = crystal cells; nr, orrnr which are evident! v Uy nuclei of the same ; k crystalline cone :pigment cells ; ret, retinute ; rh, rhabdome ; , , sensory ; their structure is as follows : n, nerve. According to Patten (A) the A peripheral nerve fibre enters a ommatidium is, apart from the corneali. n i • i . ., hypodermis, of one layer, all its elements ganghomc cell, which is in its turn passing by means of thin processes through connected with the integument by its whole thickness from the base to the means of a long slender stretched corneal lens; according to Grenacher theommatidium apart from the corneal lensconsists of two layers. tube.
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
