l88 THE STORY OF GERM LIFE. 



which they produce are poisons to them as well 

 as to the individual in which they grow, and 

 after these have become quite abundant the fur- 

 ther growth of the bacterium is checked and 

 finally stopped. Partly, also, must we conclude 

 that these hostile conditions are produced by 

 active vital powers in the body of the individual 

 attacked. The individual, as we have seen, in 

 some cases develops a quantity of some substance 

 which neutralizes the bacterial poisons and thus 

 prevents their having their maximum effect. Thus 

 relieved from the direct effects of the poisons, the 

 resisting powers are recuperated and once more 

 begin to produce a direct destruction of the bac- 

 teria. Possibly the bacteria, being now weakened 

 by the presence of their own products of growth, 

 more readily yield to the resisting forces of the 

 cell life of the body. Possibly the resisting forces 

 are decidedly increased by the reactive effect of 

 the bacteria and their poisons. But, at all events, 

 in cases where recovery from parasitic diseases 

 occurs, the revived powers of resistance finally 

 overcome the bacteria, destroy them or drive 

 them off, and the body recovers. 



All this is, of course, a natural process. The 

 recovery from a disease produced by the invasion 

 of parasitic bacteria depends upon whether the 

 body can resist the bacterial poisons long enough 

 for the recuperation of its resisting powers. If 

 these poisons are very violent and produced rap- 

 idly, death will probably occur before the resisting 

 powers are strong enough to drive off the bacteria. 

 In the case of some diseases the poisons are so 

 violent that this practically always occurs, recov- 

 ery being very exceptional. The poison produced 

 by the tetanus bacillus is of this nature, and recov- 



