I'KOIMVTION OF STEREOISOMERIC LACTIC ACIDS 179 



Schizornycetes producing levo- lactic acid ;ire rare. On the contrary, a considerable 

 n umber of species (mostly pathogenic) endowed with this property are already 

 known. Investigations on this point were first made by J. KUPRIANOW (I.) and 

 repeated by B. Gosio (I.), and it was shown that the amount of this acid 

 produced per unit of quantity of the fermented sugar varies according to the 

 species employed. 



Vibrio cholera', asiaticw (in addition to other vibrios) was found to produce 

 levo-lactic acid, whilst /Spirillum tyroyenum (Deneke) produced dextro-lactic 

 acid. On the other hand, G. LEICHMANN (I.), in 1896, showed that when 

 ordinary milk is kept at 44-5o C. instead of the lower temperatures 

 employed by Giinther and Thierfelder levo-lactic acid is invariably produced. 

 The (long-rod) fission fungus concerned in this reaction was named by LEICH- 

 MANN (II.) Bacillus lactis acidi t & name (as we have seen in 135) already in use 

 for another species of Schizomycetes as long ago as 1886. 



The kind of lactic acid produced under given circumstances by a certain 

 bacterium affords, in many instances, a valuable means for differentiating allied 

 species. For example, in the case of Bacillus typhi abdominalis and Bacterium 

 coli commune, the latter as shown by BLACHSTEIN (I.) produces dextro-lactic 

 acid from glucose, whilst the former, under identical conditions, gives rise to 

 levo-lactic acid. 



Nevertheless, the faculty of a given species of bacterium for producing a 

 definite kind of lactic acid must not be regarded as unconditional. On the 

 contrary, a good deal depends on the conditions of nutrition. The necessity for 

 the maintenance of identical conditions during experiments of this kind has 

 already been emphasised, and it should be also mentioned that the results are 

 influenced not only by the kind of carbohydrate (sugar) subjected to fermentation, 

 but also by the constitution of the nitrogenous nutrient material. For this 

 discovery we are indebted to A. PERE (I.), who showed that when ammonia salts 

 alone (unaccompanied by peptone) are at the disposal of the microbe, both 

 B. typhi abdominalis and Bacterium coli commune produce levo-rotatory lactic 

 acid from glucose. 



The separation of optically active compounds by means of Eumyceles will be 

 frequently referred to in the second volume, so we will only mention a treatise 

 by M. vox NENCKI (II.), which describes a valuable method for manipulating 

 fermenting liquids and determining their content of optically active lactic acid. 

 The characteristics of the salts of this acid have been described by T. PURDIE and 

 J. WALLACE WALKER (II.). According to F. HOPPE-SEYLER and FR, ARAKI 

 (I.), the lithium salts are the most suitable compounds to employ in experiments 

 for determining the rotatory power of the various lactic acids. 



