iv.] ARTIFICIAL COMMA-BACILLI. 67 



grms. of Grubler's peptone, made faintly alkaline, boiled and 

 filtered ; add to this a filtered boiled solution of 10 grms. of 

 Agar-agar in 900 ccm. of water). Faintly alkaline beef 

 broth or beef infusion, to which are added i per cent. Agar- 

 agnr and i per cent, peptone, is also very good. 



The comma-bacilli, sown at a point of the surface, grow 

 at 35-37 C. in the course of a few days into a translucent 

 film, with rounded or slightly indented outline ; this film 

 gradually enlarges in extent and becomes more or less 

 terraced, i.e. arranged in superimposed layers differing in 

 extent ; radiating lines probably due to shrinking of the 

 Agar-agar mixture are now to be noticed ; the central portion 



FIG. 22. FROM A CULTIVATION OF CHOLERAIC COMMA-BACILLI IN GELATINE IN 

 A GLASS DISH FOUR DAYS AFTER INOCULATION IN SPOTS. NATURAL SIZE. 



is thickest and therefore more opaque than the periphery ; 

 the whole growth after a few weeks to a few months shows 

 in transmitted light a yellowish-brown tint with denser 

 brownish spots, in reflected light it looks whitish grey. 

 In streak cultivation a film starts from the line of inoculation 

 which rapidly (in two to three days) spreads out in breadth. 



Sown into the depth of the medium, into a channel made 

 with the pointed end of a capillary glass tube or the 

 platinum wire, and kept at a temperature of35-37C., the 

 growth is always noticed after two or three days as a whitish 

 line ; this gradually increases in thickness, and the growth 

 seen under a lens appears more or less granular. 



(d) In vegetable albumen and Agar-agar mixture (Grubler's 



F 2 



