596 Journal of Agricultural Research voi. xii, no. 9 



critically the present status of the question. As the older literature 

 has been reviewed so many times that further elaboration is not neces- 

 sary, we shall pass in review only those papers of very recent date. 



Hunter and Bushnell (8) have demonstrated the presence in silage 

 of large numbers of high acid-producing bacteria, and have furnished 

 strong evidence that these organisms are mainly responsible for the 

 acid fermentation. Although their work is a most valuable one, it should 

 be borne in mind that the evidence is circumstantial and perhaps not 

 conclusive. It is rather doubtful if the data submitted justify the positive 

 conclusion that — 



The present investigation warrants the statement that acid production, common 

 to ail normal silage, is largely the result of fermentation by the Bulgarian group of 

 bacteria. 



The fact that these bacteria formed considerable acetic acid when 

 grown in alfalfa extract to which was added i per cent of glucose hardly 

 warrants the assumption that — 



Although these organisms evidently do not produce all of the acetic acid found 

 in normal silage, they must be responsible for a large per cent of it. 



Sherman (75) also noted the presence of large num.bers of the aciduric 

 bacilli in silage and reported some observations which indicated that 

 they are of significance in the fermentation process. The evidence, 

 however, was not direct and by no means conclusive. 



Hunter (7) in his work on heat production in silage has added further 

 weight to the bacterial theory of silage fermentation. Unfortunately 

 it is not possible to evaluate properly some of the interesting points 

 contained in his paper, as they are obscured by insufficient description. 

 For example, some data are given which show the difference in heat 

 formation between green kafir heated and green kafir inoculated with 

 Bacillus bulgaricus. The exact treatment in this case is not clear: If 

 the inoculation v\^as made into heated kafir, the results are of utmost 

 significance; if, on the other hand, as the caption of the graph would 

 indicate (see 7, fig. 9), the inoculation was made into unheated kafir 

 and that compared with heated kafir, the test contributes nothing to 

 the solution of the moot question. In his assumption that cell respira- 

 tion can play no part in the fermentation of silage made from dry for- 

 age. Hunter has arrived, we think, at conclusions which are, in part at 

 least, erroneous. 



In a very interesting paper Lamb (9) concludes that both factors 

 are of importance, btit that microorganisms play the larger part, espec- 

 ially in the production of acid. Following the suggestion of Rahn {10), 

 he has attempted to determine the cause of the process by the rates 

 of change in the fermentations studied. The course of the curve obtained 

 when such data were plotted was interpreted as indicating whether 

 the action was of bacterial or enzymic origin. 



