324 Mary Davies Swartz, 



Both aerobic and anaerobic cultures have been made, in neutral, 

 faintly alkaline, and faintly acid reaction, with solutions made from 

 the carbohydrates alone, and with the addition of small amounts of 

 such nutrients as beef extract or peptone to facilitate the growth of 

 the organisms. 



Anaerobic cultures in test tubes have been made by the Wright 

 method ; anaerobic cultures in Erlenmeyer flasks, by passing a stream 

 of hydrogen through for half an hour, and then sealing hermetically. 



The aerobes which have been employed all occur in the human 

 digestive tract. Both aerobic and anaerobic cultures from the 

 faeces of human subjects have also been used, in conjunction with 

 soil bacteria from street sweepings. 



Tests for the presence of reducing sugar have been made by pre- 

 cipitating the carbohydrates in solution with absolute alcohol, evapor- 

 ating the alcoholic extract to dryness, taking up the residue in 2 or 

 3 cc. of water, and boiling two minutes with Fehling's solution. 



Suitable controls have been used in all cases. 



TRIALS WITH PURE CULTURES OF AEROBES. 



One per cent solutions of the preparations from dulse, Irish moss and 

 salep, neutral, acid, and alkaline in reaction, and consisting of, (1) 

 pure carbohydrate- (2) carbohydrate plus | per cent beef extract and 

 ^ per cent sodium chloride; (3) carbohydrate plus 1 per cent peptone 

 and i per cent sodium chloride, have been used as culture media. 

 Five cc. portions of each of these solutions were placed in test-tubes 

 with a pipette, and inoculated with the following organisms: B. Coli 

 communis, B. Pyocyaneus, B. Prodigiosus, B. Proteus vulgaris, 

 B. Pyogenes foetidus. 



To approximate the conditions in ordinary digestion of these car- 

 bohydrates, they were incubated for three days at a temperature of 

 37.5° C. At the end of this time, nearly all gave evidence of some 

 bacterial growth. Salep-peptone cultures of B. Pyocyaneus showed 

 a brilliant green; salep solutions containing B. Pyogenes foetidus, 

 and B. Coli in alkaline-beef extract media, had changed from trans- 

 parent colorless solutions to an opaque white jelly insoluble in water. 



The carbohydrates were then precipitated with alcohol, and after 

 standing several days were compared with controls similarly prepared, 

 to see whether any change could be observed in the nature or amount 

 of carbohydrate. The results were in all cases negative. These pre- 

 cipitates were then transferred to small folded filter papers of uniform 



