EPIDEMIOLOGY OF INFLUENZA 



497 



luxuriance. In the hands of J. T. Parker in this laboratory, this 

 method has given excellent results and it is by means of such a 

 medium that she has produced the toxic substances referred to 

 below. The fact that this fluid medium does not contain much, if 

 any, hemoglobin, but is very rich in lipoidal substances, makes us 

 believe that possibly the nutritive substances in blood necessary for 

 the growth of this bacillus may consist in the lipoidal contents of 

 the blood cells, rather than the hemoglobin. This, too, is confirmed 

 by recent observation of Avery. 25 



'The general view, however, is the one whic)? attributes to the 

 hemoglobin in the blood the nutritive function. 



FIG. 51. COLONIES OF INFLUENZA BACILLUS ON BLOOD AGAR. (After Heim.) 



A more luxurious growth of influenza bacilli may be obtained 

 by cultivation in jars in which about 1 / 10 the volume of air has been 

 replaced by C0 2 . 



For preservation of laboratory cultures of influenza bacilli, the 

 best medium is fresh, defibrinated rabbit's blood, kept at room 

 temperature in the dark. In this way, laboratory strains after 

 several generations of cultivation outside the body can be kept 

 alive for weeks and even months. They will not keep well either 

 in the ice-box or in the incubator. 



Avery, Proc. Soe. Exper. Biol. and Med., 18, 1921, 6. 



