566 EEPOET OF NATIONAL MUSEUM, 1887. 



H. G. Beyer— Continued. 



mere associates of these processes, attributing the real cause of the resulting decomposition to 

 chemical ferments, others, though believing in the causation of fermentation by microorganisms, 

 looked at these processes as physiological ones or else attributed them to a certain power of 

 adaptability possessed by certain microbes to different conditions of life. 



Lister was, perhaps, the first clearly to point out the fact that the peculiar and characteristic 

 fermentative process by which milk becomes sour is initiated or directly caused by a certain 

 species of microbe. "While, however, Lister had proved this fact, it did not necessarily follow 

 from his experiments alone that the same process might not also be called into existence by a 

 chemical ferment produced by the lacteal glands, and which was contained in the milk when 

 it left these glands. 



The matter, therefore, even after Lister's famous experiments, remained as undecided as 

 ever, and the contention which has grown up between chemists and biologists for ages past 

 had not been diminished in any way. 



In the mean time our methods of bacteriological research having been greatly improved 

 by the patient and admirable researche . of Prof. Eobert Koch, it had become necessary to 

 reinvestigate this whole question. The task has, indeed, been most ably performed by Dr. 

 Heuppe, whose researches will be found embodied in a recent contribution to our knowledge 

 of lactic acid fermentation and fermentation in general, published in the Mittheilungen d. kaiger- 

 lichen Gesundheitsamteg, Berlin, 1884. 



In this paper Heuppe has, we think, successfully demonstrated the fact that lactic acid 

 fermsntation, or the process of the souring of milk, by whk h the sugar contained in milk is con- 

 verted into lactic and carbonic acids, is directly dependent on or caused by a certain definite 

 variety of microorganism, the morphological and physiological character of which renders it 

 sufficiently distinct from any other known microbe. 



Heuppe has demonstrated his point in the following manner : First, by showing that this 

 particular organism is constantly associated with lactic-acid fermentation ; second, by sepa- 

 rating it from other microorganisms ; third, by cultivating it outside the original media in 

 which it occurs, so as to separate chemical by-products ; fourth, by the inoculation of pure 

 cultures into the proper media producing the characteristic decomposition ; fifth, by ascer- 

 taining the biological conditions under which this process of fermentation is brought about in 

 the best manner. 



Although Heuppe himself is exceedingly guarded in his conclusions, the results obtained 

 by him from the very accurate series of experiments made according to the most modern and 

 advanced methods, will, no doubt, be fully realized by even those who are but slightly familiar 

 with the history of fermentation and the long struggle which has existed for ages, and still exists 

 between chemists and biologists with regard to the nature and causes of fermentation. This 

 alone would, no doubt, form sufficient pretext for a critical examination and repetition of at 

 least a portion of Heuppe's experiments. But aside from this, and in spite of the fact that 

 importation of Heuppe's lactic-acid germ is most likely to be an almost daily occurrence on 

 this side of the Atlantic, the identity between it and the germs which cause the same decom- 

 position in American milk must be proven by the same methods and experiments, in order to 

 make this mere supposition a certainty. 



"With this object in view, I gladly took advantage of an opportunity kindly offered to me 

 this summer by Drs.E. D. Salmon and Theobald Smith, of the Bureau of Animal Industry, TJ. 

 S. Department of Agriculture, of working out this problem in their well-equipped laboratory. 



In repeating Heuppe's experiments, so far as th is was done by me, it was, of course, thought 

 best to follow out the same course of experimenting and to use the same methods as were 

 used by him, and the first question, therefore, which naturally arose was, What microorgan- 

 isms, if any, do we find in sour milk as it occurs in our market ? 



Bacterium lactis may be described as a short, thick, plump, little rod, distinctly ovoidal in 

 shape, about half as broad as long, and varying in length from 1 to 2/jl, its breadth remaining 

 tolerably uniform. The best specimens may be found in milk cultures, the smallest in beef- 

 infusion-pepton-gelatine cultures. As the bacterium lengthens a slight constriction about its 

 middle portion becomes noticeable, which soon broadens and deepens, giving rise, just before 

 complete division takes place, to the figure-8 form. This form becomes more especially notice- 

 able in preparations stained with methyl-violet, which leaves a very minute central portion 

 of the protoplasm unstained. The germ does not liquefy gelatine, and when examined on the 

 hollow side it is found to be motionless. "With regard to spore-formation our experiments 

 have not been attended by very positive results, although everything else seems to indicate 

 that they do form spores. The settlement of this question will form one of the subjects of 

 future investigations. 



The results of the foregoing experiments have led me to agree fully with those obtained by 

 Heuppe, namely, lactic-acid fermentation, or the process of the souring of milk during which 

 the sugar contained in the latter is converted into lactic and carbonic acids, is directly de- 

 pendent or caused by the life and growth of a certain definite variety of microorganism, the 



