2o6 Theobald Smith 



days and the fluid will be strongly acid. The gas is composed 

 of about 2 volumes of H and i volume of CO;^. In bouillon 

 containing 2 per cent, cane sugar the gas production goes on 

 in cultures of some varieties. It accumulates more or less 

 slowly and the ratio of CO^ to H varies.* 



The Hog-cholera Group of Bacilli. — While forms differing 

 more or less in physiological and cultural features are thrown 

 together as .5. colt communis, pathogenic forms having much 

 closer affinities, in fact scarcely any points of difference, are 

 carefully separated and named. This anomaly is due to the 

 practical importance of pathogenic species. Of the hog 

 cholera bacillus itself, an organism of considerable economic 

 importance as well as of marked pathological interest, I have 

 examined in the course of the past seven years a number of 

 cultures from widely different regions of our country. Some 

 of these possessed minor varietal characters, among which 

 may be included a considerable variation of pathogenic power. 

 With a few exceptions the gas producing phenomena are re- 

 markably uniform. In case of these exceptions, one of them 

 a culture now seven and a half years old, the gas production 

 is somewhat reduced quantitatively. Whether this is an 

 original peculiarity or a result of prolonged cultivation I am 

 not prepared to state. 



They all possess the power of fermenting glucose in pre- 

 cisely the same manner as B. coli, but they are incapable of 

 producing gas in bouillon containing cane sugar and milk 

 sugar. The absence of any action on milk sugar in this 

 group is correlative with the absence of any power to coagulate 

 milk. Even after weeks of sojourn in the thermostat and sub- 

 sequent boiling, milk cultures remain fluid. In this group I 

 also include a still unnamed bacillus from the genital passages 

 of a mare, B. enteriditis , Gartner", and B. typhi vucrium, 

 lyoffler''. These are the only ones which I have carefully ex- 

 amined. There are probably others, found in different 

 countries, which belong to this group of pathogenic bacteria. 



In the following table are included several distinct physio- 

 logical varieties of the hog cholera bacillus : — 



*The products of the fermentation induced by B. coli have been more 

 or less exhaustively studied by Baginsky", Pere' and Scruel". 



