BACILLUS INFLUENZA 539 



of this bacillus because of its nutrient qualities and not by virtue 

 of its oxygen-carrying properties. Although the presence of hemo- 

 globin seems to be a necessity for the successful cultivation of the 

 bacillus, the quantity present need not be very large. Ghon and Preyss l 

 showed that an amount too small to be demonstrated spectroscopically 

 sufficed for its growth. 



Other substances which, added to neutral or slightly alkaline agar, 

 have been used for the cultivation of influenza bacilli are the yolk of 

 eggs 2 (not confirmed) arid spermatic fluid. 3 None of these, however, 

 is as useful as the blood media. Symbiosis with staphylococci, 4 too, 



FIG. 114. COLONIES OF INFLUENZA BACILLUS ON BLOOD AGAR. (After Heiin.) 



has been found to create an environment favorable for their develop- 

 ment. 



Influenza bacilli do not grow at room temperature. Upon suitable 

 media at 37.5 C. colonies appear at the end of eighteen to twenty-four 

 hours, as minute, colorless, transparent droplets, not unlike spots of 

 moisture. These never become confluent. The limits of growth are 

 reached in two or three days. To keep the cultures alive, tubes should 



i Ghon und Preyss, Cent. f. Bakt., xxxv, 1904. 

 3 Nastjukoff, Cent. f. Bakt., Ref., xix, 1896. 



Cantani, Cent. f. Bakt., xxii, 1897. 



* Grassberger, Zeit. f. Hyg., xxv, 1897. 



