XXVIII. AN ADDITIONAL NOTE ON THE WHOOPING- 

 COUGH BACILLUS* 



By DRS. J. BORDET and O. GENGOU. 



It has seemed to us well to give certain additional information 

 concerning our study of the whooping-cough bacillus in order to 

 facilitate the work of other bacteriologists who are interested in 

 the subject. 



Our researches during the last year have fully confirmed our 

 conviction as to the authenticity of the organism we described at 

 that time as the causal agent in whooping-cough. We shall not 

 repeat the arguments which we gave in our former article, but 

 will simply add that we have in every instance found a strong 

 sensitizing power in the sera of children that have recovered from 

 whooping-cough. 



A culture medium which we have already described — a mixture 

 of rabbit blood and agar containing a little glycerinated extract 

 of potato — still seems to be the best for isolating the organism.! 

 In growing the organisms the most important fact is that the whoop- 

 ing-cough bacillus, at least in the first culture, grows very slowly; 

 at least 2 days in the thermostat is necessary for the appearance 

 of colonies, and these may remain very small unless the medium 

 is most carefully prepared. Little or no growth takes place if the 

 medium has become dried or if enough contaminating organisms 

 of rapid growth are mixed with the colonies and monopolize the 

 nutrient properties of the medium. If these unfavorable con- 



* Note complementaire sur le microbe de la coqueluche. Annales de l'lnstitut 

 Pasteur, Vol. 21, 1907, p. 720. 



f The following observation is of some importance in obtaining a growth. 

 The defibrinated blood added to the fluid agar should be very carefully mixed 

 with it by shaking. The blood is of greater specific gravity than the agar, and, 

 unless they are carefully mixed, the upper part of the medium is composed of agar 

 that contains very little blood, and therefore when the tubes are slanted their 

 surfaces offer a very unfavorable culture medium. 



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