BACTERIA OF THE STOMACH AND INTESTINE. 671 



sugar, and that Bacillus coli communis finds the most favorable 

 conditions for its growth in the large intestine. 



Brieger, in 1884, isolated from faeces and carefully studied two 

 bacilli, one of which has since been called by his name. This is a 

 non-liquefying bacillus which is very pathogenic for guinea-pigs, 

 and which in its morphology and characters of growth closely re- 

 sembles the Bacillus coli communis of Escherich. Indeed, a num- 

 ber of non-liquefying bacilli, differing but slightly in their morpho- 

 logical and biological characters, have been obtained by various 

 investigators from the alimentary canal of man and the lower ani- 

 mals, and it is still a question whether they are to be regarded as 

 distinct species or as varieties of the "colon bacillus " of Escherich. 

 The bacillus obtained by Emmerich from cholera cadavers in Na- 

 ples belongs to this group, and, if not identical with the colon bacil- 

 lus, resembles it so closely that its differentiation is extremely diffi- 

 cult. Brieger's bacillus forms propionic acid in solutions containing 

 grape sugar. A second bacillus obtained by him from the same 

 source resembles the " pneumococcus " of Friedlander ; this causes 

 the fermentation of saccharine solutions, with production of ethyl 

 alcohol. 



Bienstock (1883) isolated four species of bacilli from normal faeces, 

 two of which are comparatively large and resemble Bacillus sub- 

 tilis in their morphology and in the formation of spores. A third 

 species is described as an extremely slender pathogenic bacillus, re- 

 sembling the bacillus of mouse septicaemia. The fourth species is an 

 actively motile bacillus which forms end spores, causing the rods to 

 have the form of a drumstick. This is said to cause the decomposi- 

 tion of albumin, with production of ammonia and carbon dioxide. 

 Later researches do not sustain Bienstock's conclusion that the ba- 

 cilli described by him are the principal forms found in normal faeces. 



Among the species encountered by Escherich, in addition to those 

 mentioned above (Bacillus coli communis and Bacillus lactis aero- 

 genes), are the following : Proteus vulgaris, found three times in 

 meconium, and constantly in the faeces of dogs fed upon flesh ; Strep- 

 tococcus coli gracilis, found in meconium, but not during the period 

 of nursing, is constantly present in the intestine when a flesh diet is 

 employed. 



The intestine of carnivorous and omnivorous animals contains a 

 greater number of bacteria than that of the herbivora, and in the 

 large intestine they are far more numerous than in the small intes- 

 tine (De Giaxa). Sucksdorf has enumerated the colonies developing 

 from one milligramme of faeces from individuals on mixed diet. He 

 obtained an average of 380,000 from a series of observations in which 

 the maximum was 2,300,000 and the minimum 25,000. 



