. A text-book of invertebrate morphology. Invertebrates. TYPE ARACHNID A. 439 cup-shaped structures, the cavity of the cup being filled by the cuticular cornea and its wall transformed into the retina, which is continuous at the margins of the cup with the gen- eral hypodermis. The retinal cells are of two kinds, viz., large sensory cells and smaller interstitial cells. Each sen- sory cell is surrounded by pigment and bears upon its lateral walls a chitinous secretion which, with the corresponding secretion of contiguous cells, forms a rhabdom. The nuclei of the cells are situated nearer their
. A text-book of invertebrate morphology. Invertebrates. TYPE ARACHNID A. 439 cup-shaped structures, the cavity of the cup being filled by the cuticular cornea and its wall transformed into the retina, which is continuous at the margins of the cup with the gen- eral hypodermis. The retinal cells are of two kinds, viz., large sensory cells and smaller interstitial cells. Each sen- sory cell is surrounded by pigment and bears upon its lateral walls a chitinous secretion which, with the corresponding secretion of contiguous cells, forms a rhabdom. The nuclei of the cells are situated nearer their inner than their outer ends, and behind them in Euscorpius highly refractive spheres occur imbedded in the cells, constituting what have been termed the phaospheres. Upon its inner wall the retina is lined by a basement-membrane continuous with that lying below the general hypodermis and perforated by the fibres of the optic nerves which come into contact with the inner ends of the sensory cells. In the Spiders, in which there are six or eight eyes arranged upon the dorsum and sides of the cephalothorax, the ante- rior dorsal pair differs in structure from the remaining ones. In both forms of eyes (Fig. 200) the cuticular cornea (c) rests. Fig. 200.—Eyes of Spidek. A, Antbriok, and B, Postbeior Eye (after Bertkau from Korschelt and Heider), fi = rods. r = retina. I = lens. i = tapetum lucidum. « = vitreous layer. upon a corneal hypodermis, (the vitreous cells, v), but the arrangement of the retina differs greatly. In the anterior dorsal pair {J) it is composed of a layer of elongated cells (r) whose nuclei are situated towards their inner ends, while near. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original McMurrich, J. Playfair (James Playfair), 1859-1939. New York, H. Holt and Company
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1894
