THE BACILLUS OF INFLUENZA. 311 



alkaline-methylene-blue, but best when treated for five 

 minutes with a dilution of Ziehl's carbol-fuchsin in 

 water (the color of the solution should be pale red). 

 (Fig. 63.) It is decolorized by the method of Gram. 



Fig. 63. 



Bacillus of inflnenza in spatnin. °f'7^.,^7^ / 



It develops only at temperatures ranging from 26° 

 to 43° C. Its optimum temperature for growth is 

 37° C. It possesses the peculiarity of developing upon 

 only those artificial culture-media to which blood or 

 blood-coloring-matter has been added. Its cultivation 

 is best conducted and its development most satisfac- 

 torily observed by the following procedure : over the 

 surface of a slanted agar tube or over agar-agar solid- 

 ified in a Petri dish smear a small quantity of sterile 

 blood (not blood-serum). A bit of the mucus from the 

 sputum of the influenza patient is then taken up with 

 sterilized forceps or on a sterilized wire loop, rinsed 

 off in sterile bouillon or water and rubbed over the 



