The Anatomy, Histology, and Embryology of Limulus Polyphemus - Tapa blanda

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1880 edition. Excerpt: ...eye is situated, i. e., on each side of the median spine near the front edge of the carapace, the chitinous integument suddenly becomes much thinner; the integument is divided as in the cornea of the compound eye into three portions, an outer thin yellow clear portion; a much thicker finely laminated part with fine granules and capable of being stained reddish; and a much thicker clear part, which has about a dozen layers, not seen in the third inner layer of the integument next to the edge of the compound eye. The integument is also penetrated throughout by canals filled with connective tissue. The surface of the cornea is slightly convex. Next to the base of the large corneal lens, there is a chitinous portion (p) which is less dense than the adjoining clear part, becoming stained a pale crimson by picro-carmine. Just as-in the facets of the compound eye the laminated part of the cornea extends conically into the base of the corneal lens, forming a cone within the larger lens; this part (h) is less dense than the lens, and is usually more distinctly conical than the lens itself. The latter is a large solid mass of chi ' tin, with two curved lines (plate 5, fig. 13, cl) in some examples, showing a slight ten dency to lamination; in form it is longer than thick, and very obtusely rounded at the end, being as thick near the end as at the base; in form therefore the lens differs decidedly from that of the corneal lenses of the compound eye. That the corneal lenses of both simple and compound eyes of Limulus are solid is proved by the fact that they do not stain reddish like the laminated portion of the cornea and adjacent integument, and also because they are excavated as solid cones projecting inwards;,from the cast chitinous crust of the...