178 STUDIES IN IMMUNITY, 



thai present in the exudate was not only wholly satisfactory, but 

 as complete and absolute as possible.* 



The cultural comparison of this organism with the influenza 

 bacillus shows that the two are essentially different. On blood 

 media the whooping-cough bacillus grows much less readily during 

 the first generation, but much more luxuriantly subsequently. 

 It grows a little more slowly. Its growth is whitish and thicker 

 and without the bluish, diaphanous appearance of the influenza 

 growth. It does not show as great a need of hemoglobin as does 

 the influenza bacillus, but when grown subsequently on colorless 

 ascites-agar it develops in a white, oily, and moist layer which 

 becomes so opaque that in 2 or 3 days it is almost as thick as 

 a culture of typhoid bacillus on ordinary agar.f The whooping- 

 cough bacillus has less tendency to pleomorphism and involution. 

 It does, to be sure, become smaller during several generations on 

 our blood-culture medium, but it soon regains its primitive form 

 on being inoculated in a liquid medium and then reinoculated on 

 solid media. Although it fails to grow on the usual media steril- 

 ized in the autoclave, such as agar, gelatin and ordinary bouillon, 

 it develops well in such liquid media as 1 per cent glycerinated 

 bouillon with equal parts of rabbit blood or serum, although under 

 these conditions its form frequently changes. J 



Although our researches on the subject are not finished, it is 

 probable that the organism secretes substances that produce local 

 effects rather than general intoxication, that is to say, which pro- 

 voke an irritating and even a necrotizing action. The organism 

 when injected subcutaneously or intraperitoneally in the guinea- 

 pig is fatal only in very large doses. On injecting a little of the 



* We use, as a stain, carbolated toluidin blue prepared in the following manner: 

 Toluidin blue (Grubler), 5 grams; alcohol, 100 c.c.; water, 500 grams; complete 

 solution is allowed and then 500 grams of 5 per cent carbolated water is added. 

 The stain is filtered 1 or 2 days later. This blue is preferable to ordinary carbo- 

 lated methylene blue. 



t These remarks naturally refer only to the organism that has been accus- 

 tomed to growing on artificial media; it is by no means sure that the organism will 

 grow in the first generation on ascites-agar. 



t This fact separates it usually from the other bacteria that grow on ordinary 

 media noted by certain observers (Afanassiew, Czaplewski and Henzel, Vincenzi, 

 Manicatide, Leuriaux, etc.), and are demonstrable in quite pure whooping-cough 

 sputa. There is no need of considering these organisms in detail. 



