PARASITIC BACTERIA. 135 



called false membranes. It never enters any of 

 the tissues of the body, although attached to the 

 mucous membrane. It grows vigorously in this 

 membrane, and there secretes or in some way 

 produces extremely violent 

 poisons. These poisons 

 are then absorbed by the 

 body and give rise to the 

 general symptoms of the 

 disease. Much the same is 

 true of the bacillus which 

 causes tetanus or lockjaw Y\G. ^g. Tetanus bacillus. 

 (Fig. 29). This bacillus is 



commonly inoculated into the flesh of the victim 

 by a wound made with some object which has 

 been lying upon the earth where the bacillus 

 lives. The bacillus grows readily after being in- 

 oculated, but it is localized at the point of the 

 wound, without invading the tissue to any extent. 

 It produces, however, during its growth several 

 poisons which have been separated and studied. 

 Among them are some of the most violent poi- 

 sons of which we have any knowledge. While 

 the bacillus grows in the tissues around the 

 wound it secretes these poisons, which are then 

 absorbed by the body generally. Their poison- 

 ing effects produce the violent symptoms of the 

 disease. Of much the same nature is Asiatic 

 cholera. This is caused by a bacillus which is 

 able to grow rapidly in the intestines, feeding 

 perhaps in part on the food in the intestines and 

 perhaps in part upon the body secretions. To 

 a slight extent also it appears to be able to in- 

 vade the tissues of the body, for the bacilli are 

 found in the walls of the intestines. But it is 

 not a proper parasite, and the fatal disease it 



