xii] PATHOGENIC BACILLI ; GROUP C 261 



derived from the oral cavity or fauces, literally crowded 

 with masses of what, when duly stained, looked exactly 

 like the typical influenza bacilli. 



I. Culture in broth. — Broth-tubes containing a pure 

 culture of the influenza bacillus remain quite limpid ; at 

 the bottom of the fluid there are noticed already after 

 twenty-four hours, but better after forty-eight hours, a few 

 whitish-grey, irregular granules or flocculi, which during the 

 next two or three days increase in size and number and 

 form at the bottom of the tube greyish-white nebulous fluffy 

 masses ; when shaken they break up into whitish-grey 

 granules and flocculi, but soon again settle at the bottom 

 of the fluid, leaving the rest of the broth perfectly limpid. 

 In four or five days (at 37° C.) the growth has reached its 

 maximum. Sub-cultures show the same characters, but we 

 generally noticed that as the number of removes increases 

 the broth has a tendency to show slight turbidity after one, 

 two, or three days' incubation, minute granules sticking to 

 the wall of the tube and showing themselves also in various 

 layers of the fluid. 



Furthermore, in successive subcultures it is noticed that 

 the amount of growth (floccular masses) at the bottom of 

 the fluid is not invariably the same, being decidedly less in 

 the later than in the earlier sub-cultures. 



A point of great interest is the comparatively rapid death 

 of the bacillar elements in the broth cultures. Unless the 

 transmission is carried on within two, three, or four, up to 

 seven days, it will be found that the sub-cultures are sterile; 

 broth cultures from eight to ten days old are very uncertain, 

 broth cultures a fortnight old yield no living organisms to 

 subsequent sub-cultures. But if the sub-cultures are set up 

 every two or three days we did not find a limit to the 

 number of generations to which some of our cultures could 



