NOT DESCRIBED IN PREVIOUS SECTIONS. 447 



" Action on Milk and Litmus Reaction, Milk remains liquid, and milk 

 colored blue with litmus is changed to pink. 



" Gas Production. Not observed in milk or potato cultures. 

 " Relation to Gelatin. Does not liquefy gelatin. 

 "Spores have not been noticed." 



Bacillus Coli Communis in Peritonitis. The researches of A. 

 Frankel show that Bacillus coli communis may be obtained in pure 

 cultures from the exudate into the peritoneal cavity in a considerable 

 proportion of the cases of peritonitis, and there is good reason for 

 believing that in these cases it was the causs of the inflammatory 

 process. Thirty-one cases were examined by Frankel, with the fol- 

 lowing result: Pure cultures of Bacillus coli communis were obtained 

 in nine cases ; of Streptococcus (pyogenes ?) in seven ; of Bacillus 

 lactis aerogenes in two ; of " diplococcus pneumonise " in one ; of 

 Staphylococcus pyogenes aureus in one. Of the remaining eleven 

 cases, seven gave mixed cultures, and in three of these Bacillus coli 

 communis was the most abundant species. The author referred to 

 has also shown that pure cultures of Bacillus coli communis injected 

 into the cavity of the abdomen of rabbits cause a typical peritonitis. 

 The present writer has frequently obtained the same result in experi- 

 ments made with this bacillus. It would appear, therefore, that the 

 peritonitis which so constantly results from wounds of the intestine 

 is probably due, to a considerable extent, to the introduction of this 

 microorganism from the lumen of the intestine, where it is con- 

 stantly found, into the peritoneal cavity, where the conditions are 

 favorable for its rapid development. 



90. BACILLUS LACTIS AEROGENES. 



Synonym Bacillus lactis aerogenes (Escherich). 



Obtained by Escherich (1886) from the contents of the small intestine of 

 children and animals fed upon milk ; in smaller numbers from the faeces of 

 milk-fed children, and in one instance from uncooked cow's 

 milk. 



Morphology. Short rods with rounded ends, from 1 to ^ 



2 n in length and from 0.1 to 0.5 V- broad; short oval and e t % / 



spherical forms are also frequently observed, and, under 99 



certain circumstances, longer rods 3 fi may be developed : $"* / g 



usually united in pairs, and occasionally in chains contain- 

 ing several elements. In some of the larger cells Escherich 

 lias observed unstained spaces, but was not able to obtain FlG< 

 any evidence that these represent spores. 



This bacillus stains readily with the ordinary aniline Si*-*? 1 

 colors, but does .not retain its color when treated by Gram's 

 method. 



Biological Characters. An aerobic (facultative anaerobic), non-liquefy- 

 ing, non motile bacillus. Does not form spores. Grows in various culture 

 media at the room temperature more rapidly in the incubating oven. 

 Upon gelatin plates, at the end of twenty-four hours, small white colonies 

 are developed. Upon the surface these form hemispherical, soft, shining 

 masses which, examined under the microscope, are found to be homogeneous 



