BACTERIOLOGY OF WHOOPING-COUGH 17 



a perfectly clear fluid above. When inoculated, this becomes turbid 

 as a result of the growth, such a culture being very convenient for 

 inoculations. The bacilli grow in milk, and also in the various kinds 

 of sugar media, if a little hemoglobin is added, but no change occurs 

 in any of them. 



Only a very small amount of hemoglobin is required for the growth 

 of these bacilli. One may dilute blood with sterile water many 

 times, and if a few drops of this laked solution is added to agar a 

 clear transparent medium, scarcely colored at all, is obtained, upon 

 which the bacilli grow in abundance. This is a very convenient 

 medium to use for their culture. The organism is rather delicate 

 and must be transferred every five days to make sure of growth. 

 They seem to live somewhat longer in liquid than on solid media. 

 They are very susceptible to drying, and a temperature of 42 C. for 

 a few hours is fatal. The bacilli have been observed through many 

 successive generations without undergoing any essential change. 

 Some strains have been, transplanted every four or five days for six 

 months, and their morphology and cultural characteristics remained 

 unaltered. 



These bacilli are thrown out into the air in large numbers during 

 the coughing spell of the child, and if one is in front of the patient 

 he is sure to inhale some of them. In five cases blood-agar plates 

 were held in front of the patient from 6 to 12 inches -away during the 

 spasm, and in every instance the bacilli were isolated. There are 

 always other organisms on the plate, and usually the colonies are 

 not pure, for the bacilli are carried out from the throat in particles 

 of spray, which one would expect to contain more than one kind of 

 bacteria. With babies, where it is difficult or impossible to obtain 

 sputum, examination for the bacilli may be made in this way. 



Symbiosis. Grassberger 1 has called particular attention to the 

 occurrence of very large influenza colonies in the immediate neigh- 

 borhood of colonies of other bacteria, when grown with them 

 on blood-agar plates. He worked especially with staphylococcus, 

 but the same effect is obtained when influenza bacilli are grown with 

 many other varieties. He observed influenza colonies as large as 

 4 mm. in diameter, grown in this manner, which in pure culture 

 are usually only ^ mm. or less. Jochmann also observed this same 



1 Zlschr. f. Hyg. t 7*97, 25, p. 453- 



