474 STUDIES IN IMMUNITY. 



respiratory tract. One of us who followed her case carefully was 

 able to obtain a whitish shred of exudate that was not mixed with 

 saliva which was projected by the whoop in the first characteristic 

 crisis. The microscopical examination with Kuhne's carbolated 

 blue stain showed that this rich leucocytic exudate contained an 

 enormous number of little ovoid bacilli which were somewhat 

 elongated at times, but frequently so short as to resemble a micro- 

 coccus; in general the aspect was rather constant, the stain a pale 

 blue, and the outline of the bacillus and particularly its poles were 

 frequently more deeply stained than the center. This organism 

 was found scattered indiscriminately among the cells and was 

 at times within cells. Some of the larger organisms frequently 

 showed a little point toward the center that appeared to be walled 

 off; the majority of the bacteria were separate, but some of them 

 occurred in pairs, end to end. Gram's stain was negative. The 

 growth of the organism was so abundant and the culture was so 

 pure that it seemed reasonable to admit some causal relation be- 

 tween this organism and the appearance of whooping-cough in a 

 child whose bronchi had not previously been affected. All attempts 

 to cultivate the organism, however, were unsuccessful. The exu- 

 date, when grown on ascites-agar (ascites fluid mixed in equal parts 

 with melted agar) or on agar moistened with human or rabbit 

 blood, gave only a few colonies of unimportant cocci. Such media, 

 however, are very well suited to grow delicate bacteria; on blood 

 agar, in particular, the inoculation of sputum from cases of grippe 

 gives an abundant growth of the influenza bacillus. The sputum 

 on subsequent days showed a progressive diminution in this bacillus. 

 In short, although microscopical examination showed many organ- 

 isms, culture was unsuccessful. 



During the following years we made a bacteriological examina- 

 tion of a number of whooping-cough sputa in Brussels, the most 

 part of which we collected in hospitals. We usually used the cul- 

 ture medium which we have found very useful in growing delicate 

 bacteria, particularly those bacteria which we have studied in our 

 work on the flora of the respiratory tract.* The majority of these 



* The culture medium is prepared in the following manner: 100 grams of sliced 

 potatoes are added to 200 c.c. of 4 per cent glycerinated water. This is steamed 

 in the autoclave and, on separating the fluid, a concentrated glycerinated extract 

 of potato is obtained. To 50 c.c. of this extract is added 150 c.c. of per cent 



