496 A MANUAL OF BACTERIOLOGY 



from patients, inoculated another ten men with 10 c.c. of 

 blood from patients, and caused ten other men to inhale 

 deeply the breath and coughings of ten patients. None 

 of these thirty volunteers developed any illness. 



Some fresh light was thrown on the failure to find the 

 B. influenzce in the earlier stages of the 1918-19 epidemic 

 when it was appreciated that media containing unaltered 

 blood, particularly human, are actually inhibitory to the 

 growth of the organism, and subsequently by adopting 

 culture media containing boiled or otherwise treated 

 blood (e.g. Fleming's). B. influenzce was recovered in 

 from 65 to 90 per cent, of cases thus investigated. When 

 the cases are complicated with pneumonia, the presence 

 of the other bacteria tends to dilute, or even to cause 

 disappearance of, the B, influenzce. 



Admitting that with proper technique B. influenzce 

 can be isolated from a large proportion of cases of in- 

 fluenza, that the organism inoculated with suitable pre- 

 cautions into monkeys reproduces many of the features 

 of the human disease, and recognising the difficulty of 

 transmitting the disease even with infective material 

 (sputum, etc.) itself, a reasonable case seems to have 

 been made out for the setiological relationship of B. 

 influenzce to epidemic influenza in man. 1 



The blood-serum of patients may agglutinate the 

 bacillus, but the phenomenon is inconstant and variable. 



While the B. influenzce itself seems to be capable of 

 producing a broncho-pneumonia, the pneumonic com- 

 plications of the 1918-19 epidemic were largely due to 

 infections with haemolytic streptococci and with pneumo- 

 cocci. 



Remarkable differences In the disease occur in epidemics 

 of influenza. Thus, in the epidemic of the 'nineties, 



1 See a critical review on the subject by Fildes and Mclntosh, Brit. Journ. 

 Exper. PatJioL, i, 1920, pp. 119 and 159. 



