656 PROCEEDINGS OF SECTION I. 



As a practical method of separating food-poisoning organisms 

 of the colon type plate on bile salt lactose agar or ordinary agar, 

 and if bile salt lactose agar be used pick off white colonies (non- 

 lactose fermenters), or if ordinary agar pick off a dozen or so 

 colonies at random. Sow these on lactose peptone water and 

 throw out all acid or acid and gas formers on lactose, and investi- 

 gate only the non-lactose fermenters by testing on glucose, mannit, 

 dulcit, and cane sugar and litmus milk ; agar cultures are made 

 and stained for morphology. 



Isolation of Bacillus typhosus. — The bacillus typhosus is a 

 mannit-oxygene anaerogene. Here the procedure is first To exclude 

 all gas formers, then to prove that the bacillus (1) gives acid on 

 mannit ; (2) nil on dulcit, lactose, cane sugar or raffinose ; 

 (3) acid on sorbit ; (4) slight and permanent acidity on litmu? milk ; ^ 

 (5) is motile, and (6) gives no indol reaction, and (7) of course 

 conforms to the general characteristics of the colon group ; (8) 

 the agglutination reaction is the final criterion as to the specific 

 nature of the bacillus. The actual technique of plating, picking 

 off and testing is similar, with obvious modifications, to that 

 described for food poisoning organisms. 



Isolation of Bacillus dysenterice {Flexner). — The procedure here 

 is similar to that employed for the isolation of B. typhosus, but 

 while B. dysenterice (Flexner) agrees exactly with B. typhosus on 

 the first five sugars, glucose, mannit, dulcit, lactose and cane sugar 

 {at any rate up to 48 hours) (1) some varieties may give some 

 acidity on lactose and cane sugar after a more or less long period 

 of incubation ; (2) it ferments raffinose ; (3) does not ferment 

 sorbit ; (4) gives transient acidity followed by alkalinity on litmus 

 milk ; (5) is non-motile ; (6) gives a positive indol reaction ; and 

 '{7) the agglutination and immunity reactions may link it to one 

 of the standard types of the Flexner group, but there seem to be 

 a considerable number of strains with different powers of agglu- 

 tinability. 



Isolation of Bacillus dysenteries (5/jiga).^This organism belongs 

 to the non-mannit oxygene anaerogenes, and is thus sharply marked 

 off from the typhosus Flexner group. There are several varieties 

 whose biochemical reactions have been more or less worked out. 

 The Shiga Kruse strain (1) gives acid on glucose ; (2) no action 

 on mannit, dulcit, lactose, cane sugar, raffinose or sorbit ; (3) 

 slight acid is said to be produced on erythrit, which should therefore 

 be an important acid in differentiating it, as so few organisms 

 afiect this sugar ; (4) maltose is not fermented by the true Shiga 

 Kruse strain, but is affected by another variety ; (5) litmus milk is 

 turned faintly acid and later becomes alkaline ; (6) indol is not 

 produced ; (7) the organism is non-motile. 



1 B. typliosus is, I have found, .-iblc to blue litmus milk after a long period of incubation 

 ' t\\ <» nuHiths about . 



