446 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



Studies on the pharmacology of caffein. — (1) The experiments 

 on the comparative toxicity of callein in dilTcrent species of animals 

 and by dill'erent modes of administration were continued. Chronic 

 catlein intoxication in docs and rabbits was also studied. 



(2) Experiments on rabbits to determine the production of caf- 

 fein glycosuria indicate that doses not large enough to induce nervous 

 and muscular symptoms cause a temporary diabetes. After larger 

 doses the amount of sugar in the urine is increased. Glycosuria was 

 also produced in some, but not in all, of the cats under observation. 

 The amount of sugar in the urine of cats was much larger, however, 

 than in that of rabbits similarly treated. It was also found that 

 calcium chlorid stimulates caffein glycosuria in rabbits. 



(3) Caffein added to liver tissue and allowed to stand in the pres- 

 ence of antiseptics for several days may be almost completely re- 

 covered, thus showing that the liver does not contain an}'^ specific 

 enzym Avhich destroys caffein. 



(4) The elimination of caffein in the bile was studied in dogs, rab- 

 bits, and cats, results showing that caffein is eliminated through this 

 channel. 



(5) The effect of caffein on protein metabolism in dogs has been 

 studied with especial care during the past year. Valuable and inter- 

 esting data have already been obtained, and the work will be con- 

 tinued. 



(6) A study of the effect of caffein on the circulation of cats and 

 dogs is in progress. 



(7) The elimination of kreatin and kreatinin after the adminis- 

 tration of caffein has been continued. The results indicate increas- 

 ing eliminiation of kreatin, but the evidence is not yet conclusive. 



Toxicity of the alcohols and of other compounds in the fatty 

 ACID series. — Experiments on the comparative toxicity of ethyl and 

 amyl alcohol were conducted, considerable work being done on the 

 effect of ethyl alcohol on the protein metabolism in dogs. Because 

 of its use in the arts and in flavoring essences for food, the pharma- 

 cology of amyl acetate was made the subject of a special investigation. 

 It was found that from 4 to 6 cc injected subcutaneously caused 

 paralysis and coma in frogs. 



Some work has been done on the improvement of methods of analy- 

 sis employed in metabolism experiments. The preparation of the 

 sample for the determination of total nitrogen in feces and the deter- 

 mination of allantoin in the urine of animals have been especially 

 studied and improvements made in the usual procedures. 



CHEMICAL reagents. 



Five hundred and three chemicals were examined to check the qual- 

 ity of the reagents supplied to the Bureau of Chemistry and the 

 branch laboratories on contract, as w^ell as to other laboratories of 

 the Department. Some improvements have been made in the general 

 quality of the chemicals during the past year, and in many instances 

 the manufacturers have improved on the style of container and the 

 method of labeling. The rejections from the various lots of chemicals 

 has been about 5 per cent. Some of the rejections and the reasons for 

 same are as follows: Absolute ether, containing peroxids; absolute 

 alcohol, containing foreign organic matter and aldehydes ; citric acid, 



