34 SCIENCE PROGRESS. 



will grow upon an acid soil, produces very little lactic acid 

 when cultivated upon sterile whey, while, as Petruschky (30) 

 originally discovered, the bacterium of Escherich produces 

 more than twice the amount of acid. Milk coagulation is 

 apparently due to this development of acid and not to an 

 enzyme, and Huysse (31) has shown that cholera vibrios 

 also possess this property of acid production with consequent 

 curdling of milk. 



The researches of Blachstein (32) which were carried 

 out in Nencki's laboratory have added largely to our 

 knowledge of the biology of the bacillus typhosus. The 

 lactic acid produced by the growth of Eberth's bacillus on 

 glucose bouillon is always lsevo-rotatory and no ethyl alco- 

 hol is produced. The bacterium coli commune grown upon 

 a similar soil produces ethyl alcohol and considerable quan- 

 tities of dextro-rotatory paralactic acid. Macfadyen (33), 

 while working with Nencki, examined the contents of the 

 small intestine chemically and also for bacteria. These he 

 found especially attacked the carbohydrates within the 

 bowel. Alcohol was formed by all the isolated micro- 

 organisms and the amount produced in some cases amounted 

 to sixteen per cent, of the weight of the sugar. The lactic 

 acids present in the bowel contents were either the especi- 

 ally inactive or the dextro-rotatory paralactic acid. There 

 was apparently no evidence that any other lactic acid was 

 present. Blachstein speaks of three different activities 

 which the bacillus typhosus can exhibit according as this 

 microbe is isolated from dejecta, from the spleen, or taken 

 from subcultures. The first and last of these kinds pro- 

 duce relatively much and little lactic acid, but this is always 

 lsevo-rotatory. Calculations have shown that the small 

 intestine of the guinea pig contains about 1400 microbes, 

 and the large intestine 2000-5000 for each decigramme of 

 material. Among this vast number it may be affirmed that 

 no single microbe in the normal gut yields a la^vo-rotatory 

 lactic acid, and since Escherich's bacterium is a normal 

 occupant of the gut of infants, men and many animals, it 

 may be confidently affirmed that typhoid fever cannot be 

 spread by normal human dejecta, a view which in this 



