654 PROCEEDINGS OF SECTION I. 



Having divided the colon gro p into these two main headings 

 we can follow McConkey's classification of the serogenes, first 

 splitting into those giving acid and gas on lactose (lactose serogenes) 

 and those which do not affect lactose (non-lactose gerogenes). The 

 lactose ferogenes can theoretically be sp'it according to their action 

 on mannit, but non-mannit-lactose-gerogenes are rare, if occurring 

 at all, owe usually regard the lactose gerogenes as mannit fermenters, 

 and classify them first of a'l into McConkey's four groups, accord'ng 

 to their action on dulcit and saccharose, and further, if necessary 

 (as shewn in Table III), by their action on adonit, inosit, and 

 gelatin, and by the Vosges and Proskauer's reaction, indol forma- 

 tion, and according to whether they are motile or not. This is 

 more clearly shown on the tables. 



Turning now to the non lactose gerogenes (Table II), work at pre- 

 sent done does not enable us to draw up so clear a scheme of separa- 

 tion. It is convenient and practically useful to first split the groups 

 according to the action on mannit into mannit non-lactose aero- 

 genes and non-mannit non-lactose gerogenes. Further than this 

 my own experience tells me that dulcit is not to be relied on as 

 a means of differentiating this type, and Twort has stated that 

 some of this group, usually not fermenting saccharose, can be made 

 to ferment it. Still it can, I think, be definitely stated that if an 

 organism does give acid and gas on saccharose under four days 

 it is not a true Gaertner type. Therefore at present I think the 

 scheme in the table good enough for practical purposes. It at 

 any rate gives very useful results in my hands, and is comparable 

 to the scheme used with the lactose ccrogenes. All the non-lactose- 

 mannit-aerogenes are classified according to this scheme by their 

 action on saccharose into saccharose-mannit-non-lactose-gerogenes 

 and non-saccharose-mannit-non-lactose gerogenes. Further split- 

 ting may be made by considering the action on dulcit, but, as I 

 have suggested before, I think these organisms show inconstant 

 reactions towards this sugar. 



The other great group of the colon bacilli is the angerogene 

 group, which do not produce gas on sugars (glucose being used as 

 the test) (Table I). It may be divided into the oxygenes and 

 anoxygenes, according to whether acid is produced or not, a very 

 small number being known which produce no action on any sugar. 

 Here, however, we will consider only the oxygene angerogenes. 

 All these organisms produce acid on glucose (Table IB). 



At present it is impossible to classify this group properly, as 

 very little work seems to have been done on it. Its great interest 

 lies in the fact that three of the most pathogenic organisms of the 

 colon group lie in its confines — B. typhosus (Eberth Gaffky), B. 

 dysentericB (Flexner), B. dysenterice (Shiga). For the purpose of 

 separating these organisms mannit is the most important sugar. 

 B. Shiga Eyre, Kruse, etc., are all non-mannit anaerogenes, whereas 

 B. typhosus and B. flexner are mannit angerogenes. 



