BACTERIUM INFLUENZAS. 343 



blood-coloring-matter has been added. Its cultivation 

 is best conducted and its development most satisfac- 

 torily observed by the following procedure : over the 

 surface of a slanted agar tube or over agar-agar solid- 

 ified in a Petri dish smear a small quantity of sterile 

 blood (not blood-serum). A bit of the mucus from the 

 sputum of the influenza patient is then taken up with 

 sterilized forceps or on a sterilized wire loop, rinsed 

 in sterile bouillon or water and rubbed over the sur- 

 face of the prepared agar-agar. The plate or tube is 

 then placed in the incubator at 37 to 38 C. If in- 

 fluenza bacilli be present, they will develop as minute, 

 transparent, watery colonies that are without structure, 

 and which resemble somewhat minute drops of dew. 

 They are discrete and show little or no tendency to 

 coalesce. 



If a small bit of mucus be rubbed over the surface 

 of ordinary nutrient agar-agar, no such colonies de- 

 velop. In making the diagnosis by this method cult- 

 ures on both agar-agar containing blood (not blood- 

 serum) and agar-agar containing no blood should always 

 be made, for the reason that growth of these peculiar 

 colonies in the former and no such growth in the latter 

 are evidence that one is dealing with materials from a 

 case of influenza. 



The organism may also be cultivated in bouillon to 

 which blood has been added, if kept at body-tempera- 

 ture. The growth appears as whitish flakes. Since this 

 organism is a strict aerobe, its cultivation can only be 

 conducted on the surface of the medium used i. e., 

 where it has freest access to oxygen. It is therefore 

 inadvisable to prepare plates in the usual way. When 

 its cultivation is attempted in bouillon it is recom- 



