LEV IN E, BIOCHEMICAL STUDIES OF SELENIUM 389 



AXIMAL TISSUES 



Animal tissues also reduce sodium selenite. Fresh liver, spleen, heart, 

 lung, kidney, pancreas, small intestine, large intestine and stomach, in- 

 cubated in the presence of toluol at 37.5° reduce a 0.5% solution of 

 sodium selenite within twenty-four hours. The liver and spleen reduce 

 very quickly and most profusely. Portions of striped muscle, testicles, 

 thyroid, submaxillary gland and lingual glands give negative results. 

 Toluol-preserved, unfiltered extracts, first kept at room temperature for 

 twenty-four to thirty-six hours and then treated with sodium selenite 

 showed reduction within twenty-four hours, only in the case of liver, 

 pancreas and small intestine. Tliis result indicates that the reducing 

 power of the tissues disappears in the course of time. That the reduc- 

 tion is due to cell activity or enzyme activity is evident from the fact 

 that tissues after being heated on a water-bath for about ten minutes 

 fail to yield reduction. Fresh liver, however, heated or unheated, re- 

 duces sodium selenite. This reaction is due to the presence of chemically 

 reducing substances such as carbohydrates. Tissues to which an excess 

 of chloroform has been added show no reducing power. Chloroform itself 

 does not inhibit the reduction of sodium selenite by pure sugar solutions. 

 Filtered chloroform extracts also do not reduce, although the liver extract 

 was found to reduce on the first or second day, and the spleen on the 

 third or fourth day. The other extracts failed to show reduction, even 

 after two weeks. Reduction is probably due to an insoluble enzyme closely 

 connected with the living cell, that is, an endo-enz3rQie. Selenious acid 

 and selenic acid are also reduced, while sodium selenate is not reduced. 



SELEXIUM CO:\IPOUXDS IXJECTED IXTO THE AXi:\IAL SYSTEM 



Selenium compounds, injected into the animal system, undergo re- 

 duction. Some of the selenium escapes from the organism in the form 

 of a volatile organic selenid, some is precipitated, mostly extracellularly, 

 in the tissues as, dark red-brown granules. The liver and spleen contain 

 by far the largest amount of deposited selenium. The microscopic ex- 

 amination of the histologically stained tissues of a dog that had received 

 2 mg. selenium dioxid per kilo, of body weight, revealed the presence of 

 selenium in these two organs. AVith sodium selenite, selenium was found 

 widely distributed in the liver, spleen, kidney, lung, pancreas, heart, 

 stomach and intestine. These tissues showed marked reductions within 

 the regions of hemorrhagic clots. Other tissues showed reduction only 

 within such areas. A lethal dose of selenic acid brought about deposition 

 of the granules in the spleen and liver. The lungs, which were found 

 to be extremely congested, also showed reduction. Selenium pigmenta- 



