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. 1893 Excerpt: ...the urinary organs consist of a pair of kidneys, which are generally placed in the posterior part of the abdominal cavity. Each kidney may be considered to consist of a collection of nephridia or segmental organs (similar to those seen in the earth-worm). The kidneys pour their urinary secretion into a pair of ducts or ...
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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. 1893 Excerpt: ...the urinary organs consist of a pair of kidneys, which are generally placed in the posterior part of the abdominal cavity. Each kidney may be considered to consist of a collection of nephridia or segmental organs (similar to those seen in the earth-worm). The kidneys pour their urinary secretion into a pair of ducts or ureters, which run down, one from each kidney to open into the bladder, into a sinus common to the genital and the urinary products, or into the cloaca. Fig. 86.--Diagrammatic representation of the segmental organs (nephridia) in a segmented Worm (after C. Semper). Ds, septum; Wtr, ciliated funnels of nephridia. The ureter develops on the surface of the embryo as a groove which later becomes formed into a canal, so that although the nephridia or tubules do not open to the exterior, they open into a canal which in development is pinched off from the exterior, its walls being epiblastic in origin. In connection with each tubule or nephridium, a pouch appears, into which a coil of arterial blood vessels (glomerulus) becomes pushed, the pouch with its blood vessels being known as the Malpighian body. As a rule the ciliated funnel, which was present during development, becomes completely closed. The walls of the tubule for a considerable part of their extent are lined with glandular cells, and are richly supplied with blood vessels. The urine is derived partly from the blood as Fig. 87.--Diagrammatic representation of the kidney (segmental organs) of a Dogfish embryo (after C. Semper). JVtr, ciliated funnels; Ug, kidney duct. it passes through the glomeruli and partly from that in the vessels between the tubules. The glandular cells, which line the walls of these tubules, take up from the blood the nitrogenous waste material, and excrete it into t...
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