1 6 DAVID J. DAVIS 



dew-drop-like. They have a delicate blue color and do not hemolyze. 

 In one case (No. 15) only, did I observe a very narrow but distinct 

 clear zone of hemolysis about the colonies. This persisted through 

 two generations, and then disappeared and could not be obtained 

 again. The colonies, if not very numerous, especially on pigeon 

 blood, will sometimes grow very large. Some have been observed 

 over 2 mm. in diameter. As a rule they are J mm. or less in 

 diameter, and not infrequently, if numerous on the plate, require 

 the aid of a hand lens to be seen. They do not increase in size after 

 from 24 to 36 hours. Upon blood-agar slants they produce a delicate 

 growth and the colonies remain discrete. 



In every case, after getting the organism in pure culture on blood 

 media, it was tested on several kinds of non-hemoglobin media, 

 usually Loeffler's blood serum, plain agar, and milk. Many of the 

 strains were tested on N serum agar, serum broth, ascites agar, and 

 various kinds of sugar media. In none of these did any of the organ- 

 isms develop. Particular attention should be called to the fact that 

 there is not infrequently in human serous fluids a small amount of 

 hemoglobin, and if such fluids are used growth will occur. This 

 fact may explain some of the reports in the literature, such as that 

 of Elmassian, of organisms from pertussis cases growing upon serum 

 media. To be sure of proper results, one should examine such fluids 

 with a spectroscope before using. 



Media to which yolk of egg was added did not yield any growth. 

 Bile was added to agar, and some growth was obtained with this in 

 the first transplantation, but continuous growth did not occur. The 

 organism in pure culture did not grow on hematin agar. Upon CO- 

 hemoglobin they grow as well as upon ordinary oxyhemoglobin. 

 Inasmuch as oxygen is necessary for their growth, the CO- hemoglobin 

 made by passing a stream of CO through blood for half an hour, was 

 necessarily exposed to the air, and a small amount was consequently 

 changed back to oxyhemoglobin, which might explain this growth. 

 The abundant growth suggests, however, that the CO-hemoglobin 

 may also be available, though it is perhaps impossible to prove this. 

 Growth is obtained in liquid media to which a drop or two of blood 

 is added. Plain broth plus a small amount of pigeon's blood is a 

 good medium. The blood corpuscles soon sink to the bottom, leaving 



