464 Proceedings Columbia Biochemical Association [April-July 



intestina. Selenium dioxid and selenic acid were also reduced, but 

 sodium selenate was not. 



Selenium Compounds injected into the animal body, undergo re- 

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

 form of volatile organic selenid, some is precipitated extracellularly 

 in the tissues as dark red-brown granules, the liver and spieen con- 

 taining by far the largest amount of such deposited selenium. The 

 microscopic examination of the histologically stained tissues of a 

 dog that had received 2 mg. of selenium dioxid per kilo revealed the 

 presence of selenium in these two organs. With sodium selenite, 

 selenium was found more widely distributed: in the liver, spieen, 

 kidney, lung, pancreas, heart, stomach and intestine. These tissues 

 also showed marked reduction near hemorrhagic clots. Other tis- 

 sues occasionally exhibited reduction only within such areas. A 

 lethal dose of selenic acid was followed by deposition of the granules 

 in the spieen and liver. The lungs, which were found to be ex- 

 tremely congested, also showed reduction. Selenium pigmentation 

 with potassium selenate was slight in comparison with that produced 

 from sodium selenite, and but few granules were found in the spieen, 

 pancreas and liver. In the case of potassium selenocyanate, re- 

 duced selenium was found in the liver, spieen, lung, kidney, pan- 

 creas, heart, brain (only in hemorrhagic spots), muscle (only in 

 similar spots), and stomach, The reduction of selenium Compounds 

 seems to be a detoxicating process ; selenium itself displays very little 

 toxicity. 



Living bacteria reduce selenious acid, selenic acid and sodium 

 selenite to elemental selenium, but do not reduce sodium selenate. 

 Selenium may be also deposited from potassium selenocyanate, as a 

 result of acid decomposition. The precipitated selenium follows the 

 path of bacterial growth. For such tests, the medium used should 

 not contain reducing chemical substances such as glucose and lactose.^ 

 Reduction is proportional to the intensity of growth. Selenious 

 acid, selenic acid and, less markedly, sodium selenite, inhibit 

 growth. The amount of retardation depends upon the nature of 

 the organism. Streptococcus pyogenes was found to be more sen- 

 sitive than Bacillus coli. The bacilli of symptomatic anthrax, 

 edema, and tetanus suffer very markedly in growth, even in the 



^Levine: Biochemical studies of selenium; Biochem. Bull., 1913, ii, p. 552. 



