FORMATION OF ACIDS AND ALCOHOL. 85 



Bac. megatherium. According to the latter, this fertilizer acts as 

 follows: The Bacilli mycoides and megatherium, in the first place, 

 in a nutrient medium poor in nitrogen store up atmospheric nitrogen 

 in the soil; in the second place, they change the nitrate into ammo- 

 nia and so protect it against the denitrifying organisms. Stoklasa 

 (C. B. L. iv, 817). Lauck saw practically no value in alinit 

 (C. B. L. v, 20); Stoklasa asserts very good results by many ob- 

 servers (C. B. L. v, 350). 



Recently the question has been advanced as to whether nitrogen- 

 assimilating organisms are not more widely distributed.. Winogradsky 

 has shown in the case of a CI. Pasteurianum, closely related to the 

 Clostridium butyricum, that it utilizes the energy obtained by the 

 fermentation of sugar in the building up of organic substances from 

 atmospheric nitrogen. Similar observations have been made with 

 molds and a spirillum. 



i3. Formation of Acids and Alcohol from Carbo= 

 hydrates. 



As pointed out by Theobald Smith (C. B. xviii, 1), 

 the formation of free acids is only possible upon nutrient 

 media containing sugar. The acid formation in ordi- 

 nary bouillon only occurs because of the presence of grape- 

 sugar (very small amount originating in the meat). * Ac- 

 cording to Smith, all obligate or facultative anaerobes form 

 acids from sugar, while the strict aerobic varieties either 

 do not at all or only so slowly that the acid formation is 

 concealed by a corresponding production of alkali. Be- 

 fore knowing of this investigation we had determined that 

 all those varieties represented in the atlas which we exam- 

 ined (about sixty) produced more or less free permanent 

 acids in peptone bouillon containing 1% grape-sugar (com- 

 pare Table I). In connection with the production of 

 acids, perceptible gas-formation was either present or ab- 

 sent. Intense acid production may cause the death of 

 cultures (for example, Bact. coli, Bact. vulgare, etc.). 

 Hellstrom recently showed that sugar, since it strongly 

 favored the production of acid, especially in poor nutrient 

 media (bouillon without peptone), can shorten enormous- 

 ly the duration of the life of cultures. In peptone-free 



1 According to Th. Smith, 75% of commercial beef contains signifi- 

 cant amounts of sugar (up to 0.3%). Regarding the removal of this 

 sugar, consult the Technical Appendix under the preparation of nutri- 

 ent media. 



