374 BAOTEBIOLOGY. 



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, the bacillus of 

 influenza 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, Pfeiifer 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 

 human body. In the influenza patient it is present in 

 the catarrhal secretions, bronchial mucous membrane, 

 and the diseased lung-tissues. It may be demonstrated 

 microscopically in the mucus by cover-slip prepara- 

 tions made in the usual way and stained with diluted 

 carbol-fuchsin, referred to above. In the tissues it 

 may be demonstrated in sections stained in the same 

 solution. In the sputum the bacilli are found as masses 



