Cultivation 



399 



thick. This melts in the sterilization and forms a firm 

 layer, through which the bouillon is inoculated, warmed 

 until the paraffin melts again, then stood away until develop- 

 ment in the air-free bouillon occurs. If the paraffin be 

 found too brittle, some albaline may be mixed with it until 

 it is flexible when cool. 



The colonies of the tetanus bacillus, when grown upon 

 gelatin plates, in an atmosphere of hydrogen resemble those 

 of the well-known hay bacillus. There is a rather dense, 

 opaque central mass surrounded by a more transparent 



Fig. 120. Bacillus tetani; five-clays-old colony upon gelatin containing 

 glucose. X 1000 (Frankel and Pfeiffer). 



zone, the margins of which consist of a fringe of radially 

 projecting bacilli (Fig. 120). Liquefaction occurs slowly. 



Bouillon. The organism can be grown in bouillon, and 

 attains its maximum development at a temperature of 

 37 C. Gas is given off from the cultures, and they have a 

 peculiar odor, very characteristic, but difficult to describe. 

 The bouillon is clouded and contains a sediment. 



Gelatin. The growth occurs deep in the puncture, and is 

 arborescent (Fig. 121). Liquefaction begins in the second 

 week and causes the disappearance of the radiating filaments. 

 The liquefaction spreads slowly, but may involve the en- 



