420 HEMOGLOBINOPHILIC BACILLI 



Mucus raised from the deeper air passages is thoroughly washed in 

 sterile water and emulsified in broth or water, selecting for the pur- 

 pose purulent masses by preference, and streaked out radially from the 

 drop of blood. After twenty-four to forty-eight hours' incubation 

 the plate is examined with a lens for very minute, clear, homogeneous 

 colonies which should be removed to blood agar slants. When growth 

 occurs transfer some of it to plain agar. No further development 

 occurs unless some blood has been removed with the organisms. The 

 failure of the bacteria to develop on media free from hemoglobin is 

 distinctive. 



3. Serological. The serum diagnosis of influenza has been unsuc- 

 cessful. 



Dissemination and Prophylaxis. Influenza bacilli are distributed 

 chiefly by droplet infection. Carriers are said to be common. Prophy- 

 laxis is the same as for any respiratory disease. 



BACILLUS PERTUSSIS. 



The etiology of pertussis (whooping-cough) has been a subject of 

 controversy for several years. The problem is complicated by the 

 rather general occurrence of influenza-like bacilli in the sputum and 

 bronchial exudate from cases of whooping-cough. A clean-cut dif- 

 ferentiation between these influenzoid bacilli and Bacillus pertussis 

 described by Bordet and Gengou 1 has been difficult and has doubtless 

 led to confusion in the past. It is now generally conceded that the 

 Bordet-Gengou bacillus is worthy of serious consideration as the 

 etiological factor of whooping-cough. 



Morphology. B. pertussis is somewhat larger than B. influenzse, 

 measuring 0.3 micron in diameter and varying in length from 0.5 to 

 1.5 microns, the average length being about 1 micron. It occurs singly 

 and in groups, less commonly in pairs. The organism has rounded 

 ends; frequently it is almost ovoid in shape. The organism is non- 

 motile and possesses no flagella. Neither capsules nor spores have 

 been demonstrated. It stains poorly with ordinary anilin dyes and 

 is Gram-negative. Carbol methylene blue, carbol toluidine blue and 

 dilute carbol-fuchsin stain it readily. Methylene blue is also a satis- 

 factory stain. The organisms stain irregularly, particularly when 

 grown in artificial media. In young cultures and in sputum they 

 appear frequently with the ends stained more deeply than the centre, 

 resembling in this respect the influenza bacillus. 



1 Bull. Acad. de Med. Belgique, July, 1906; Ann. Inst. Past., 1906, xx, 731. 



