THE BACILLUS OF WHOOPING-COUGH. 475 



sputa were from cases of whooping-cough that were not studied in 

 the beginning, but were well advanced, and they contained, there- 

 fore, a rich and varied flora. We paid particular attention, ob- 

 viously, to the study of those bacteria that we had observed so 

 abundantly in a pure state in the single case in 1900 which we 

 have mentioned. 



We found, indeed, in greater or less numbers, small ovoid bac- 

 teria which were faintly stained and were quite similar to those 

 we formerly observed. The most frequent organism that we found, 

 however, was still smaller, better colored and either separated 

 or in clumps and frequently somewhat long or even filamentous. 

 This organism, which occurred in almost every case in abundance, 

 grew well on our medium; it gave, indeed, in the majority of cases, 

 the greatest number of colonies. These colonies were bluish or 

 grayish, slightly elevated in the center, rather diaphanous, par- 

 ticularly at the edges, and almost transparent in young cultures, 

 and resembled drops of dew. Microscopically the organism was 

 small, did not stain by Gram, was usually short and delicate, 

 appeared frequently as a dot, and in certain cultures, particularly, 

 showed a marked tendency to pleomorphism. Certain individual 

 bacteria were somewhat thicker and swollen and others showed 

 curious involution forms which stained faintly or unequally. This 

 organism, although it does not grow on agar or ordinary bouillon, 

 grows very well in the presence of hemoglobin. It was easy to 

 determine that we had to deal with an organism which was iden- 

 tical, or at least analogous, with the one discovered by Pfeiffer 

 in influenza and which other bacteriologists have noted in whoop- 

 ing cough and even considered as the specific bacillus — an opinion 

 which is reasonable enough when we consider its frequency. The 

 work of Jochmann and Krause,* giving a very exact description 

 of this bacillus and mentioning its need of hemoglobin, had just 



salt solution arid 5 grams of agar. This mixture is melted in the autoclave and 

 the warm fluid is placed in test tubes, 2 or 3 c.c. to a tube. The tubes are then 

 sterilized. Sterile defibrinated rabbit blood, or preferably human blood, is then 

 obtained. To each melted agar tube an equal amount of blood is added, the 

 mixture well shaken aud the tubes slanted and cooled. This medium allows the 

 growth of such delicate organisms as the meningococcus, gonococcus, the influenza 

 bacillus and, as we shall presently see, the whooping-cough bacillus. As the media 

 contains no pepton it is not very good for the growth of putrefactive saprophytes. 

 * Zeitschrift fur Hygiene, 1901, Bd. 36. 



