In the fish Xiphophorus we have detected elevated levels of pp60c-src kinase activity in a variety of tumors (n = 34) of neurogenic, epithelial, and mesenchymal origin either of hereditary etiology or induced by carcinogens. This elevation ranged from 2-fold up to 50-fold compared to the corresponding non-tumorous tissue and up to 6-fold compared to the highest activities found in any of the normal organs. The level of elevation parallels the degree of malignancy in melanoma and in tumors of mesenchymal origin. In fish bearing tumors of hereditary etiology kinase activity was also elevated in the non-tumorous brain, while in fish bearing induced tumors, kinase activity was elevated only in the cells of the neoplasia.

A study by Mann arid others ( '17 to '20) of the morphology of the extrahepatic biliary passages in species with and without a gall bladder revealed no differences bearing on the functional significance of the organ. However, on studying the choledocho-duodenal sphincteric mechanism in these two classes of animals, a definite difference was found. The pressure in the common bile duct required to overcome the sphincteric resistance mas distinctly less in animals devoid of a gall bladder.&Master ('22) directed his attention to the possibilitj-that animals which do not possess a gall bladder may concentrate bile in the hepatic ducts. H e used the common mouse which has a gall bladder and the rat which does not. McAlaster made the interesting observation that rat's hepatic bile contains eight times more pigment than that of the mouse, although the volume of bile secreted per gram of liver was about the same in both animals. Thus, i t appeared as if the liver of the rat secretes a concentrated bile and may possess in its intrahepatic mechanism the functional equivalent of the gall bladder. This suggested the hypothesis that animals not having a gall bladder may compensate for its absence by secreting a concentrated bile. This possibility was supported by Higgins' study of the morphology of the intrahepatic duct system of the r a t and iiiouse ( '26). He found that although the rat, even in embryo, 365

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The APS Journal Legacy Content is the corpus of 100 years of historical scientific research from the American Physiological Society research journals. This package goes back to the first issue of each of the APS journals including the American Journal of Physiology, first published in 1898. The full text scanned images of the printed pages are easily searchable. Downloads quickly in PDF format.

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