Land and Fresh-Water Shells; An Introduction to the Study of Conchology

Land and Fresh-Water Shells; An Introduction to the Study of Conchology

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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. 1892 edition. Excerpt: ...winter months, and the question naturally occurs to us whether or not we must look upon it as reserve nutrient material. The cells lining the intestinal tract are ciliated. The liver, digestive gland, or hepato-pancreas lies between the anterior adductor muscle and the pericardium, and on either side of the stomach, into which it pours its secretion through several ducts. It secretes trypsin and a diastatic ferment, and the extract of the gland is active in either an acid, a neutral or an alkaline medium. There are no calcareous cells, the cells present being granular and ferment cells. The Organs Of C1rculat1on.--The heart consists of two auricles and a pear-shaped median ventricle, situated in a pericardium, which communicates with the glandular portion of the nephridium by several reno-pericardial apertures. The pericardial cavity is pierced by the intestine, the ventricle by the rectum.. Between each auricle and the ventricle there is an auriculo-ventricufar valve consisting of pocket-shaped segments, which only admit the blood from the auricle into the ventricle. From the anterior end of the ventricle the anterior aorta arises and runs, along the dorsal surface of the rectum; from its posterior end the posterior aorta arises and runs along the ventral surface of the rectum. The anterior aorta passes into the visceral mass behind the anterior retractor muscle, and divides into a visceral and a pedal artery, the former of which supplies blood to the digestive and generative organs, 11 the latter to the foot, besides giving off a labial branch to the labial palps, and a pallial m branch to the mantle and anterior adductor muscle. The posterior aorta gives branches Fig I9._Diagram of the to the mantle, body-wall, and posterior ad-heart of a...show more

Product details

  • Paperback | 34 pages
  • 189 x 246 x 2mm | 82g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236590279
  • 9781236590275