BACILLUS INFLUENZA 



337 



or chains, usually lying together in thick, irregular clusters without 

 definite parallelism. 



Isolation and Cultivation. Isolation of the influenza bacillus is 

 not easy. Pfeiffer * succeeded in growing the bacillus upon serum-agar 

 plates upon which he had smeared pus from the bronchial secretions of 

 patients. Failure of growth in attempted subcultures made upon agar 



.'-rytx.g 



> 



FIG. 112. BACILLUS INFLUENZA. Smear from pure culture on blood agar. 



and gelatin, however, soon taught him that the success of his first culti- 

 vations depended upon the ingredients of the pus carried over from the 

 sputum. Further experimentation then showed that it was the blood, 

 and more particularly the hemoglobin, in the pus which had made growth 

 possible in the first cultures. Pfeiffer made his further cultivations 



1 Pfeiffer, loc. cit. 



