Staining 489 



as the formation of an endotoxin sufficiently active to ex- 

 plain the symptoms, and the fixation of complement by the 

 serum of the infected animal. This organism, therefore, 

 presents itself as sufficiently meritorious to maintain the 

 field for the present. 



Morphology. The organisms, as found in the sputum, oc- 

 cur as very minute ovoid rods of about the same size as the 

 influenza bacillus. They measure approximately 1.5 fi in 

 length by 0.3 u in breadth. They do not remain united 

 as chains or rods, but separate as individuals. They are 





Fig. 1 60. The Bordet-Gengou bacillus of whooping-cough. Twenty- 

 four-hour-old culture upon solid media containing blood (Bordet- 

 Gengou). 



somewhat pleomorphous, yet the variations are not con- 

 siderable. Involution forms are not common. There are 

 no spores, no flagella, no motility. 



Staining. The organisms do not hold the stain well. 

 Most of the bacilli are pale, some contain uncolored areas 

 or vacuoles. In some cases the ends of the bacilli appear 

 more deeply stained than the middle. They do not stain 

 by Gram's method. The discoverers recommend that the 

 organism be stained with 



Toluidin blue 5 ^ Dissolve and add 500 of 5 per cent. 



Alcohol 100 X aqueous carbolic acid. After two 



Water 500 j days filter. 



Isolation. The organisms occur in almost pure cultures 

 in the whitish expectoration which escapes from the bronchi 



