Vital Resistance 



355 



The colonies upon agar-agar are similar but effect no liquefaction. 

 If blood corpuscles be distributed throughout the medium, a rather 

 broad zone of hemolysis is occasioned by the tetanolysin . 



Gelatin. — The growth occurs deep in the 

 puncture, and is arborescent. Liquefaction 

 begins in the second week and causes the 

 disappearance of the radiating filaments. 

 The liquefaction spreads slowly, but may 

 involve the entire mass of gelatin and resolve 

 it into a grayish-white syrupy liquid, at the 

 bottom of which the bacilli accumulate. 

 The growth in gelatin containing glucose is 

 rapid and the medium becomes filled with 

 bubbles of gas before it melts. 



Agar-agar.^ — The growth in agar-agar 

 punctures is slower, but similar to .the 

 gelatin cultures except for the absence of 

 liquefaction. In agar-agar containing glu- 

 cose the gas production may break up the 

 medium. 



Bouillon. — The organism can be grown 

 in bouillon without difficulty, when once 

 habituated to the medium. The bouillon 

 should be heated to drive off the air, then 

 rapidly cooled and the transplantation 

 made. If there be a depth of lo cm. the 

 bacilli grow readily in the lower half of the 

 fluid. If the surface be covered with liquid 

 paraffin before the final sterilization and 

 inoculation, they grow throughout the 

 entire medium. The organism attains its 

 maximum developme'nt at a temperature 

 of 37°C. No change except a well- 

 marked cloudiness appears in the bouillon. 

 After about two weeks growth ceases and 

 the bacilli settle to the bottom leaving the 

 medium fairly clear again. 



Milk is favorable for the development 

 of the tetanus bacillus. There is no 

 coagulation. Litmus milk is acidified. 



Potato. — Upon potatoes under strict 

 anaerobic conditions the bacilU grow but 

 slightly. 



Vital Resistance.- — The tetanus spores may remain alive in dry 

 earth for many years. Sternberg says they can resist immersion in 

 S per cent, aqueous carbolic acid solutions for ten hourfe, but fail 

 to grow after fifteen hours. A 5 per cent, carbolic acid solution, to 



Fig. 122. — Tetanus 

 bacillus; glucose-agar 

 culture, five months old 

 (Curtis). 



