504 EXPERIMENT STATION EEOOED. [Vol.88 



In order to investigate tiie acid production of fermentations of B. welchii 

 and B. sporogenes, a critical study was made of Dyer's inetliod of separation of 

 volatile fatty acids in a mixture (E. S. K., 37, p. 13). The method, while satis- 

 factory in dealing with a mixture of two volatile acids, was unsatisfactory 

 with a mixture of unknown acids, and the following modification was used in 

 the present investigation: 



A portion of the fermented liquid was distilled exhaustively to determine the 

 total amount of volatile acids present and another portion distilled as a simple 

 acid mixture according to Dyer's method. This indicated the highest and low- 

 est acids in the mixture. Fractionated portions of a series of separate steam 

 distillations were then collected, the total amount of acid in the fractions cal- 

 culated from the distilling rate of the mixture, and chemical tests applied to 

 the concentrated distillates of the fractions. Finally, an artificial mixture of 

 acids was prepared from a study of the data so obtained and its rate of dis- 

 tillation compared with that of the fermentation liquid. The authors state 

 that the method is tedious in application and affords only approximate results, 

 but is useful in giving important information regarding the acids produced by 

 various organisms. 



The results with B. welchii and B. sporogenes show that large quantities of 

 volatile acids are produced, of which butyric acid is a constant component. In 

 the action of B. sporogenes on milk, caproic and valeric acids are formed. 

 Propionic acid was not detected, but its presence is not excluded. Formic 

 acid is not present. Forty per cent of the total acid produced is nonvolatile. 

 The nature of these acids has not yet been ascertained. 



Contributions to the biochemistry of pathogenic anaerobes. — III, The 

 effect of acids on the growth of Bacillus welchii (B. perfringens) and B. 

 sporogenes (MetchnikofE), C. G. L. Wolf and J. E. G. Harris (Biochem. Jour., 

 11 (1917), No. 3-4, pp. 213-245, figs. 8).— Investigations on the effect of acids 

 on the growth of B. perfringens and B. sporogenes are reported, together with 

 the results of an examination of the behavior of the acids used with nutrient 

 media. 



The addition of acids to liquids containing large amounts of buffer sub- 

 stances produces a complex effect on the true reaction of the media due partly 

 to the type of acid and partly to the nature and content of the buffer sub- 

 stances in the mixture. With the less highly dissociated acids a point is soon 

 reached where successive amounts of the acid affect the reaction but slightly. 



The action of acids on the growth of the bacteria studied affects (1) the 

 latent period of growth (the more highly acid the medium the greater time 

 elapses before signs of growth are observed) ; (2) the final reaction at which 

 growth ceases (with a given acid and varying initial concentrations, a series 

 of reactions is obtained which can be represented by a curve which is indi- 

 vidual for each acid) ; and (3) the total inhibition of growth (the fermenta- 

 tion of both organisms is inhibited by a rise of hydrogen ion concentration 

 which may merely delay growth or may stop it entirely). The Inhibiting 

 effect of all acids is the same. 



The authors conclude that the results of these investigations confirm their 

 earlier views (E. S. R., 38, p. 483) that the treatment of gas gangrene infections 

 by means of acid solutions, highly buffered, is worthy of trial. 



Further observations on the influence of phenol and of cresylic acid on 

 the concentration of antitoxic sera by the Banzhaf (1913) process, Annie 

 HoMEB (Biochem. Jour., 11 (1917), No. 3-4, pp. 277-282) .—The author reports 

 that the difficulties in the technique of the Banzhaf process for the concentra- 

 tion of antitoxic sera and the tendency of the end-products to become cloudy 

 may be obviated hy the addition of 2 per cent of sodium chlorid and from 



