Zinc intervenes with a certain specificity in one group of metabolic changes, those related to carbohydrates. Both pancreas "A" cells, which manufacture glucagon, and B cells which produce insulin, contain large amounts of zinc. Zinc regulates glucose metabolism through its influence on insulin. Zinc and insulin give insoluble combinations, Zinc chloride retarding the action of insulin. (176) A diet rich in glucose depletes the Langer haus islets of zinc, (177) while protein and lipids, or even fat, increase the zinc content of the pancreas. (178) With alloxan, the islets lose their physiological capacity to store zinc. (179) IndirecUy zinc appears to have anti D activity.

A similar anti D activity for zinc can be seen in the prostate, which is particularly rich in this element. Conceivably, zinc's role would be to favor the persistence of spermatozoids. The capacity to utilize zinc is lost in the abnormal prostate. In adenomatous hypertrophy of the prostate, zinc values decrease. (180) They decrease still more with cancer of the prostate. (181) Although cancer has been induced by excessive administration of zinc, the element's role in pancreas and prostate seems to be indirect, through the metabolic changes it influences. Calcium is antagonistic to zinc, which is to be expected considering the opposite fundamental biological groups to which they belong.

It is interesting to note the influence exerted by the oral administration of zinc powder upon radiation effects in mice of C3H strain receiving lethal doses of 1500 r. In different experiments in which 85 to 100% of the controls died in less than twelve days, the mortality rate for animals given zinc ranged from 25 to 50%. In one group, a mortality rate of 15% was observed. There was a much weaker effect when nickel was incorporated in food. No effect at all could be obtained with iron.

Mercury

Mercury, a member of the IIB series was studied. Theoretically, it should act upon the sulfhydryl groups, and thus limit the processes in which these groups take part.

A series of compounds in which mercury is present in the anion, and which are routinely utilized as therapeutic agents because of their diuretic action and their effects on electrolyte metabolism, was investigated. Because of their well known diuretic effect, we initially used them in patients with generalized anasarca. We extended their use to cases with localized edema which could be related to tumors with local alkalosis. It was noted that the mercurial diuretic, in addition to influencing water and sodium excretion, changed other systemic analyses toward type A, although only temporarily. However, when these substances were administered over long periods of time, other effects were observed which could not be attributed to diuretic action. In animals with slowly growing tumors, mercury was found fixed with a degree of selectivity within these lesions. After treatment for a certain time, peritumoral fats became rich in mercury, as recognized macroscopic ally through abnormal ash color and confirmed by histochemical analysis. It was interesting to note that mercury appeared largely in the necrotic part of tumors. A beneficial influence upon evolution of tumors was seen, if a type D offbalance was present.

Bismuth

Bismuth, from the VA series was studied. We utilized available anti luetic compounds. Again localization in peritumoral fats was seen, with the fats this time becoming abnormally reddish. Neither in animals nor in patients could other important effects be recognized.