Nutrition Investigations. 325 



weight, previously prepared. The alcoholic filtrates were tested for 

 sugar; the precipitates were dried, and their weight compared with 

 that of the control. It was thought that this rather crude method 

 would show whether any considerable amount of the carbohydrate 

 had disappeared. The results were so largely negative that weighings 

 of every precipitate were not made. There seemed to be a slight loss 

 of dulse, in some of the cultures of B. Proteus vulgaris, B. Pyogenes 

 foetidus, and B. Coli communis, but repetition of these experiments 

 allowing the organisms in question to grow two weeks, not only in 

 dulse but also in salep media, did not justify any conclusion that an 

 appreciable amount of carbohydrate had disappeared. 



All tests for reducing sugar were negative. 



Four per cent solutions of Irish moss, and two per cent solutions 

 of limu manauea were then prepared, with reactions and additions ot 

 nutrient material as described in the first series of experiments. These 

 formed firm jellies, which were used to study the possibility of Hque- 

 faction or gas formation. Stab cultures were made, and grown at a 

 temperature of 25°-30° C. for one to three weeks. No Hquefaction 

 or gas formation was observed in any case. 



TRIALS WITH IvnXTURES OF AEROBES. 



Mixtures of B. Pyocyaneus, B. Prodigiosus, B. Proteus vulgaris, 

 and B. Pyogenes foetidus, were used, also mixtures of faecal and soil 

 bacteria. These were first inoculated into nutrient bouillon, the 

 former from pure cultures, the latter from human faeces and street 

 sweepings, and incubated 24 hours. Five cc. portions of these cultures 

 were then introduced into 50 cc. of neutral solutions of each of the 

 different carbohydrates, in small Erlenmeyer flasks, and these cul- 

 tures allowed to grow for four weeks at 37.5° C. At the end of this 

 time, no marked change had taken place save in the salep culture of 

 B. Pyocyaneus, B. Proteus vulgaris, B. Pyogenes foetidus and B. 

 Prodigiosus. This had changed from a colorless, semi-transparent, 

 slightly mucilaginous fluid, to a firm, white opaque jelly, insoluble 

 in water, but readily soluble in dflute alkali; a phenomenon already 

 observed with this carbohydrate in cultures of B. Coli communis and 

 B. Pyogenes foetidus. No liquefaction had taken place with Irish 

 moss nor limu manauea. 



The carbohydrates were then precipitated with alcohol, the alco- 

 holic extracts tested for sugar, and the precipitates hydrolyzed by 

 boiling with 2 per cent hydrochloric acid, neutralized, made up to a 



