Congressional Edition Volume 3258

Congressional Edition Volume 3258

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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. 1895 edition. Excerpt: ... external covering of the gland is made up of two more or less distinct layers of fibrous tissue, the outer one being continued posteriorly in a ribbon-like ligament running backward and inserting itself upon the joint of the jaw (fig. 18, e). A short ligament on the side facing the skull attaches the gland firmly to the latter, and a third one below connects with the external pterygoid muscle (fig. 15, c). At the anterior end of the gland the capsule continues as the outer covering of the duct which carries the poison from the gland to the fang. This duct, in its normal position, makes a sudden upward curve (fig. 18, -') uuder the eye, descending from which it follows the posterior wall of the pit and finally passes over the rounded outer front edge of the maxillary bone, at the base of which it meets the upper opening, or inlet, of the canal through the fang. Until Prof. Jeffries Wyman, in I860, and, about simultaneously, Dr. Christopher Johnston,"published opinions to the effect that the poison duct does not enter the canal of the fang, it was generally held that it actually continued inside of the channel. This latter view has been revived quite recently by Dr. F. Niemann, who not only describes this arrangement, but figures longitudinal and transverse sections of it as seen by him in a crotaloid snake, Bothrops lanceolatus. The longitudinal section is reproduced here as fig. 19, the transverse one as fig. 20. The latter shows at a1 the poison canal lined with the duct, which, even inside of the fang is characterized by its epithelial lining. As this opens up the question again, and makes future research necessary, and as Mr. Niemann seems to be ignorant t of the investigations referred to, it may be well to quote their evidence a...
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Product details

  • Paperback | 416 pages
  • 189 x 246 x 22mm | 739g
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236552512
  • 9781236552518