284 CLINICAL BACTERIOLOGY. 



monoxid hemoglobin. Exposure of blood-agar tubes to a tem- 

 perature of 70 C. (158 F. ), and even boiling of the hemo- 

 globin, failed to prevent entirely the development of the in- 

 fluenza-bacilli. Pfeiffer was then led to believe that the iron- 

 content of the hemoglobin was the important factor, but he was 

 unable to cultivate the bacilli in culture-media containing iron 

 other than that of the blood. 



It may be mentioned further that all kinds of blood exhibit 

 the same specific activity with relation to influenza-bacilli. 

 Pfeiffer obtained growth upon the blood of rabbits, guinea- 

 pigs, pigeons, and fish, and in more luxuriant degree and more 

 speedily on pigeon's blood which is rich in hemoglobin than 

 on human blood. 



Resistance of Influenza-bacilli. Influenza-bacilli are 

 destroyed in a few minutes when exposed to a temperature 

 of 60 C. (140 F.). They cease to develop at a temper- 

 ature of 43 C. (109.4 F.), but they are only coagulated, 

 not destroyed, for if tubes that have been exposed for 

 forty-eight hours to a temperature of 43 C. (109.4 F.), 

 and have remained sterile, are then exposed to a tempera- 

 ture of 37 C. (98.6 F.), colonies will yet develop abun- 

 dantly. In unsterilized drinking-water the bacilli die 

 quickly in from twenty-four to thirty-six hours. Upon 

 blood-agar and in bouillon they retain their vitality for from 

 fourteen to eighteen days, and in moist sputum they appear 

 to preserve their infectivity for at least fourteen days. The 

 influenza-bacilli are quite sensitive to drying. When dried 

 in blood or sputum at a temperature of 37 C. (98.6 F.), 

 they succumb in an hour or two, and when dried at room- 

 temperature, within not more than from thirty-six to forty 

 hours. 



Occurrence of Influenza-bacilli. The influenza-bacilli 

 occur regularly in the secretions of influenza-patients. In 

 the secretion of the nasal cavities the specific bacilli have 

 been found in enormous numbers ; although generally 

 associated with other microorganisms, yet, however, in 

 preponderating number. The secretion in a case of ordi- 

 nary coryza, on the other hand, is remarkably free of bac- 

 teria, being almost sterile. The sputum in cases of bron- 

 chitis and pneumonia complicating influenza is viscid, 

 mucopurulent, globular, and not seldom also purulent and 

 confluent, in color often yellowish green, not rarely pure 

 white and only seldom rusty brown, and it contains the 



