This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1899 Excerpt: ...representing all of these structures, and in other cases even these have vanished. The objection to the idea that the cells have vanished is to be found in the fact that they are so well developed over the distal face. This point can only be settled by a study of the development of the eye, but one other suggestion may ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1899 Excerpt: ...representing all of these structures, and in other cases even these have vanished. The objection to the idea that the cells have vanished is to be found in the fact that they are so well developed over the distal face. This point can only be settled by a study of the development of the eye, but one other suggestion may not be out of place. A comparison of this eye with that of Amblyopsis will suggest the homology of the anterior cell mass in the latter case, with the pigment cells always present between the retina, and the irideal pigment layer in the former species. This correspondence is further strengthened by the fact that frequently the pigment in T. rosae over the front of the eye is in more than one layer of cells. Since, however, I was unable to arrive at an entirely satisfactory explanation of the origin of this pigment mass in Amblyopsis, it will not help us much, should the two structures be homologous. Attention may be called here to the fact that both in Amblyopsis and in the present species the lens--and therefore the lost pupil--are not situated at the distal pole of the eye but above this point, and that both in regard to the pupil and the eye in general the location of the two pigment masses is the same. The pigment is granular, not prismatic. The lens: This is the only structure of the eye concerning which Kohl has not made any mistake. It is a small group of cells closely crowded together and about 10 or 12 ju in diameter (Figs. 54a and 55). There are no indications of fibrilation or the result of any other histogenic process; it appears as an aggregation of indifferent cells. On its surface there are at times cells that are evidently of an epithelial nature being flattened so that their sections appear much longer than deep. It lies at t...
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Add this copy of The Eyes of the Blind Vertebrates of North America: I. to cart. $38.69, good condition, Sold by Bonita rated 4.0 out of 5 stars, ships from Newport Coast, CA, UNITED STATES, published 2012 by Nabu Press.