Vital Resistance 



343 



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

 cent. Liquefaction begins in the second week and causes the dis- 

 appearance 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. 



Agar-agar. — The growth in agar-agar 

 punctures is slower, but similar to the gela- 

 tin cultures except for the absence of 

 liquefaction. 



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 in- 

 oculation, they grow throughout the entire 

 medium. The organism attains its maxi- 

 mum development at a temperature of 

 37°C. Gas is given off from the cultures, 

 and they have a peculiar odor, very char- 

 acteristic, but difficult to describe. The 

 bouillon is clouded and contains a sediment. 



In bouillon containing sugar considerable 

 gas is formed in the fermentation tube. 

 Both CO2 and H2S are formed. 



Milk is favorable for the development of 

 the tetanus bacillus. There is no coagula- 

 tion. Litmus milk is acidified. 



Potato. — Upon potatoes under strict anae- 

 robic conditions the bacilli grow but slightly. 



Vital Resistance.— The tetanus spores 

 may remain alive in dry earth for many 

 years. Sternberg says they can resist im- 

 mersion in 5 per cent, aqueous carbolic acid 

 solutions for ten hours, but fail to grow after 

 fifteen hours. A 5 per cent, carbolic acid 

 solution, to which 0.5 per cent, of hydro- 

 chloric acid has been added, destroys them 

 in two hours. They are destroyed in three hours by i : 1000 bi- 

 chlorid of mercury solution, but when to such a solution 0.5 per cent. 

 of hydrochloric acid is added, its activity is so increased that the 



Fig. 126. — Tetanus 

 bacillus; glucose-agar 

 culture, five months old 

 (Curtis). 



