BACTERIUM INFLUENZA. 335 



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- 

 mended, in order to favor the free diffusion of oxygen, 

 that the depth of fluid be very shallow. 



Contrary to what might be supposed, bacterium 

 influenzse has very little tenacity of life outside of the 

 diseased body. It is destroyed in from two to three 

 hours by rapid drying, and in from eight to twenty- 

 four hours when dried more slowly. Cultures retain 

 their vitality for from two to three weeks. The organ- 

 ism dies in water in a little over a day. As a result of 

 these observations, Pfeiffer does not believe the disease 

 to be disseminated by either the air or the water, but 

 rather by direct infection from the catarrhal secretions 

 of the patients. 



This organism has not been found outside of the 



