338 EXPERIMENT STATION RECORD. 



tions, pure cultures for Emmenthaler cheese, studies on properties of Russian export 

 butter, laboratory work in zymology, the application in wine making of cultures of 

 yeast, investigations of disease in faulty wines, selection and improvement of yeast, 



and instructions for the use of pure yeasts. — P. FIREMAN. 



An experimental study of the chemical products of Bacillus coli communis 

 and Bacillus lactis serogenes, L. F. Rettger (Studies Rockefeller Inst. Med. Research, 

 1 ( 1904), AH. il; reprinted from Am r. Jour. Physiol., 8 (1903), No. 4, PP- 284-293).— A 

 report is given of studies of the colon bacillus and the closely associated B. lactis 

 serogenes, to determine some of the chemical products of these organisms. 



It was found that these organisms failed to bring about a very marked decomposi- 

 tion in peptone bouillon. On the other hand, an egg-meat mixture underwent rapid 

 and extensive transformation. The common products of the colon bacillus were 

 indol, skatol, phenols, aromatic oxy-acids, skatol-carbonic acid, hydrogen sulphid, 

 mercaptan, tyrosin, leucin, and tryptophan. Alhumoses and peptone were present 

 in very small amounts, a fact which is contrary to general belief. 



It is thought that probably the bacteria peptonize proteids, but that the albumosefl 

 and peptone formed are immediately broken up by the organisms or their enzyms, 

 and are, therefore, detected with great difficulty. />'. coli communis caused more rapid 

 and profound decomposition than B. lactis serogenes, the former producing its opti- 

 mum results within 2 or 3 weeks, while for comparable results the second organism 

 required from 8 to 10 weeks. 



When bacterial digestion progressed beyond a certain point the intermediate 

 products, such as peptone, amido acids, etc., gradually disappeared from the mix- 

 tures. Indol persisted for a longer time. The disappearance of the intermediate 

 products is thought to be due to their further cleavage and the formation of still 

 simpler bodies yielding ultimately carbon dioxid, methan, etc. 



Studies of media for the quantitative estimation of bacteria in water and 

 sewage, S. De M. Gage and G. O. Adams (Reprinted from Jour. Infectious Diseases, 1 

 (1904), No. 2, pp. 358-377). — Attention is called to the fact that the media in general 

 use for quantitative work give inconstant results in determining the total number 

 of bacteria in a given volume of water. In addition, different results are given for 

 different classes of water, periods of incubation, etc. The authors present a number 

 of facts having an important bearing on the composition and preparation of media 

 which, if adopted, would probably serve as a basis for improvement and more accu- 

 rate methods of quantitative bacterial analysis. 



Results of the investigations on composition and preparation of different media are 

 given. It is said that standard gelatin and agar beef broth are sources of consider- 

 able variation. The amount of nutrient matter in beef infusion made by the usual 

 methods varies through wide limits. Of the 2 best commercial peptones, Merck's 

 and Witte's, the higher bacterial counts were obtained on media made from the 

 latter. 



Studies made of plain agar with various kinds of natural water showed that, in a 

 majority of cases, the bacteria naturally present in a given water will develop in 

 greatest numbers in a medium made with the same water. Salts naturally present 

 in commercial agar have a detrimental effect which may be overcome by washing 

 out the salts in a preparation of the medium. Media made with glycerin will 

 develop more bacteria than the same media without it. The pure cultures of differ- 

 ent kinds of bacteria on standard gelatin, agar, or Nahrstoff agar, the highest counts 

 were obtained on gelatin and the lowest on Nahrstoff. A reduction in the amount 

 of Nahrstoff in the Nahrstoff agar from 1 per cent to 0.5 per cent resulted in a con- 

 siderable increase in the number of bacteria observed in various waters. When 

 cooked in alkaline solutions, the albumoses of Nahrstoff undergo changes in compo- 

 sition which render them better food material for bacteria than is the case with the 

 commercial product. 



