and Laboratory Methods. 1757 



upper portion of the tube to expel the air and slip a well fitting rubber cap over 

 the hot test tube. 



Babes and Puscarin (1890) use high layers of two per cent, glucose agar in 

 tubes. After inoculation they expose the tubes to 80°C. for a short time, push 

 the plug down nearly to touch the surface of the medium and then pour liquified 

 paraffin on top of the plug. 



Ucke (1898) recognizes in glucose a two-edged sword, and attributes the 

 frequent failures in the cultivation of anaerobic bacteria to the use of glucose. 

 Although a more vigorous- growth is formed on glucose medium, the spores, if 

 formed at all, are less numerous ; degeneration forms are apt to develop, and the 

 virulence of the organism is lessened. He holds that if vigorous growth and 

 spore producing material shall be obtained, media without sugar should be 

 used. 



Other reducing agents: Kitasato and Weyl (1890) tested the action of a 

 large number of reducing agents in alkaline media on the development of anae- 

 robic bacteria. Their purpose was to find a substance of a greater reducing 

 power than glucose, and which at the same time would not exert a harmful 

 influence on the bacterial development. They demonstrate that the addition to 

 the culture medium of Pyrocatechin CgH4(OH)2, the sodium salt of Amidonaph- 

 tol-monosulphonic acidC^ ^HgOHNHjSOgNa, sodium indigo sulphonate Cj gHg 

 N20o(S03Na)2, Sodum formate HCOgNa, in quantities of 0.1 per cent, exerted 

 a favorable influence on the anaerobic growth, while other reducing reagents, 

 such as Hydroxylaminehydrochloride NH2(0H)Hcl, Resorcin CgH4(OH)2, 

 Hydroquinone C6H4(OH2), Pyrogallol C6H3(OH)3, Acetaldehyde CH3COH, 

 BenzaldehydeC6H5COH,phenylhydrazinehydrochlorideNH2— NH(C6H,5Hcl), 

 etc., etc., either did not affect the culture materially, or exerted a strong poison- 

 ous action on the microorganisms. The authors especially recommend the use 

 of sodium sulphonate (use 0.1 per cent.). This agent is valuable, however, as an 

 indicator of the reducing effect of certain bacteria rather than as a reducing 

 agent in itself. 



Buchner first recommended litmus to indicate changes of reaction caused by 

 bacteria. Later, Cohen proposed its use as a reduction indicator. This is import- 

 ant, as many bacteria, and especially anaerobic forms, reduce litmus rapidly to a 

 colorless leucosubstance, which, upon access to oxygen, colors red or blue accord- 

 ing to the reaction changes. 



Novy observed that the addition of litmus favors to a certain extent the 

 growth of the microorganisms, and that it exerts a protecting influence over the 

 anaerobic bacteria. Cultures of the bacilli of tetanus, black leg and malignant 

 oedema retain their vitality even in liquid media exposed to the air for months 

 if they are colored with litmus. 



Trenkmann (1898) recommends the addition of a few drops of a ten per cent, 

 solution of sodium sulphide NagS to bouillon ; take 20 c. c. of nutrient medium 

 and two drops of a ten per cent, solution of Na2S. The author cultivated the 

 bacillus of black leg successfully in such a medium in the presence of air. He 

 admits, however, that NaoS gradually decomposes by the action of COo in the 

 atmosphere, forming Na2C03 and H2S, As soon as this action takes place the 



