116 THE ACUTE SELF-LIMITED INFECTIONS 



the vegetative rod has the power of going into this 

 resistant stage very quickly when it meets unfavorable 

 environment. The rods grow best at 37 C. or 98 F. 

 The spores are killed at 105 C., 221 F., when exposed 

 ten minutes to streaming steam. They are destroyed 

 by chemicals as follows: 5 per cent, carbolic acid in 

 ten hours; 5 per cent, carbolic acid plus 0.5 per cent, 

 hydrochloric acid in two hours; 1 to 1000 corrosive 

 sublimate in three hours; 1 to 1000 corrosive sublimate 



- 



FIG. 33. Tetanus bacilli with spores in distended ends. X 1100 

 diameters. (Park.) 



plus 0.5 per cent, hydrochloric acid in one-half hour; 

 1 per cent, silver nitrate in five minutes. When dried 

 the tetanus spores will live several years. Sunlight 

 very slowly kills them. Most animals are susceptible 

 to the tetanus bacillus or its toxins. Rats and birds 

 are the least, while horses and man are the most 

 sensitive. 



Tetanus Antitoxin. The toxin of the tetanus bacillus 

 is one of the most virulent poisons known. For ex- 

 ample, TOO oV UTO cubic centimeter or ^5\T oil minim 



