44 2 Whooping-cough 



as individuals. They are somewhat pleomorphous, yet the varia- 

 tions are not considerable. 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.. . < } ,-,. , , 



Alcohol ioo Evolve and add 500 of 5 per cent, aqueous 



Water 500 J 



carbolic acid. After two days filter. 



Isolation. The organisms occur in almost pure cultures in the 

 whitish expectoration which escapes from the bronchi in the begin- 

 ning of the disease. Later they become few and may disappear, 

 though the symptoms of the disease persist. 



Fig. 1 68. The Bordet-Gengou bacillus of whooping-cough. Twenty-four- 

 hour-old culture upon solid media containing blood (Bordet-Gengou). 



Cultivation. The cultures were secured upon a special medium 

 made as follows: 



II. Potato extract (made as above) .. 50 cc. ) Boil, dissolve, filter, and 

 0.6 per cent, aqueous Nad ...... 150 cc. f tube; 2 to 3 cc. to a 



Agar-agar ...................... 5 gm. J tube. 



III. To each tube add an equal volume of defibrinated rabbits' (or, better, 

 human) blood before cooling to the point of coagulation. Permit the tubes 

 to solidify in the oblique position. 



At first the growth is scant, but upon transplantation grows better 

 and better, until finally it may be made to grow upon other media, 

 such as blood-agar, ascitic agar, or broth to which blood or ascitic 

 fluid has been added. The organism is a strict aerobe. It grows 

 best at 37C., but also grows at temperatures as low as 5 to ioC. 



