426 Diphtheria 



in the form of a flocculent precipitate which has a tendency 

 to cling to the sides of the glass, and leave the bouillon clear. 

 Spronck * found that the characteristics of the growth 

 of the diphtheria bacillus in bouillon, as well as the amount 

 of toxin produced, vary according to the amount of glucose 

 in the bouillon. He divides the cultures into three types: 



Type A. The reaction of the bouillon becomes and remains acid, 

 the acidity increasing. The bacilli accumulate at the bottom of the 

 clear liquid. The toxin-production is meager. 



Type B. There is no change from alkalinity to acidity, but the 

 original alkalinity of the bouillon steadily increases. The culture is 

 very rich, the bottom of the flask shows a considerable sediment, the 

 liquid is cloudy, and a delicate growth occupies the surface. The 

 toxicity is very great. 



Type C. In a few days the reaction of the culture becomes acid, 

 and then later on changes to alkaline. During the acid period the 

 liquid is clear, with a white surface growth. When the alkalinity 

 returns, the bouillon clouds and the surface growth increases in thick- 

 ness. Sediment accumulates at the bottom of the flask. The toxicity 

 of the culture is much less than in Type B. 



Spronck regards the varying reactions as depending upon 

 the fermentation of the glucose, and asserts that the most 

 luxuriant and toxic cultures are those grown in bouillon in 

 which no glucose is present. To exclude as much of the 

 undesirable sugar as possible, he makes the bouillon from 

 the stalest meat obtainable, preferring to secure it when 

 just about to putrefy. Of the meats experimented with, 

 beef was found to be the best. 



Zinnof found that digested brain added to the culture 

 bouillon greatly facilitated the growth of diphtheria and 

 tetanus bacilli and increased the toxin-production. 



Blood-serum. The bacillus grows similarly upon blood- 

 serum and Loffler's mixture. 



Potato.- Upon potato it develops only when the reaction 

 is alkaline. The potato growth is not characteristic. 



Milk. Milk is an excellent medium for the cultivation of 

 Bacillus diphtheriae, and is possibly at times a medium of 

 infection. Litmus milk is useful for detecting the changes 

 of reaction brought about by the alkalinity, which at first 

 favors the development of the bacillus, being soon replaced 

 by acidity. When the culture becomes old, the reaction 

 again becomes strongly alkaline. This variation in reaction 

 seems to depend entirely on the transformation of the sugars. 



*"Ann. de 1'Inst. Pasteur," Oct. 25, 1895, vol. ix, No. 10, p. 758. 

 f'Centralbl. f. Bakt.," Jan. 4, 1902, xxxi, No. 2, p. 42. 



