TETANUS 127 



was able to reproduce the typical disease in 

 animals. 



Bacillus tetani is a rather long, slender o ^ ^ 



rod, and when in the spore stage pre- ' J </ s* 



sents the appearance of a small pin or b \* ' 



drumstick, as the spore is always situ- f 



FIG. 21. 



ated at the extreme end of the rod, and Bacuim tetani 



in spore stage. 



is three or four times the size of it. In 

 the vegetative state there is nothing characteristic 

 in its appearance, but in the spore stage it is easily 

 discerned among many other organisms, besides 

 being slightly motile. 



The tetanus bacillus stains readily with ordinary 

 dyes, but its cultivation is attended with extreme 

 difficulty. Growth is slow; the first colonies not 

 showing before the end of three days. The growth 

 liquefies gelatin and blood-serum, and produces a 

 small amount of gas, giving out a disagreeable charac- 

 teristic odor. In the vegetative state the bacillus of 

 tetanus possesses no extraordinary amount of resist- 

 ance, readily succumbing to heat and to chemicals, 

 but the spores of Bacillus tetani possess wonderful 

 powers of resistance. They will survive one hour 

 of dry heat at 80 C. (176 F.) but are killed by five 

 minutes' exposure to moist heat at 100 C. (212 F.). 

 They will resist the action of 5 per cent carbolic acid 



