CHARACTERS OF THE BACILLUS 



473 



minute oval rods scarcely larger than the influenza bacillus. 

 They stain rather faintly with ordinary stains, and their margin 

 and extremities are often more deeply coloured than the centre, 

 which may appear as an uncoloured spot; they are Gram- 

 negative and do not form spores. In cultures they present the 

 same characters and are less pleomorphous than the influenza 

 bacillus (Fig. 140). They are specially numerous at the beginning 

 of the disease, and they may be found in large numbers in almost 

 pure culture in the opaque whitish sputum expectorated from the 

 bronchi ; as the disease advances they become scanty, and may 

 disappear when the 

 symptoms of the disease 

 are still prominent. 

 Bordet and Gengou suc- 

 ceeded in obtaining pure 

 cultures on the blood- 

 agar medium described 

 on p. 44, and this was 

 found to be the most 

 suitable of all the media 

 tried. In the first cul- 

 tures growth is very 

 scanty and may be in- 

 visible, but later it 

 becomes much more 

 abundant, and sub-cul- 

 tures may also be 



,., ,. FIG. 140.1 Film preparation from a twenty- 



readily made on ordm- f our hours > cu i tur e of the bacillus of whoop- 

 ary serum-agar media. ing-cough. (Bordet-Gengou). 

 As compared with that Stained with carbol-fuchsin. xlOOO. 



of the influenza bacillus, 



growth is thicker and less transparent and the margins are 

 more sharply marked off; the presence of haemoglobin, though 

 favouring the growth, is not so essential as in the case of 

 the latter organism. The organism is a strict aerobe, and in 

 the case of cultures in fluid media, e.y. serum bouillon, the 

 tubes ought to be placed in a sloped position, in order to 

 expose a greater surface to the air. Bordet and Gengou 

 completely confirmed the observations mentioned above as to the 

 very frequent, almost constant, presence of influenza-like bacilli. 

 They obtained growths of these organisms, and on comparing 

 them with their own bacillus found that distinct cultural 



1 We are indebted to Dr. Bordet for the culture from which this preparation 



was made. 



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