192 THE STORY OF GERM LIFE. 



diphtheria bacillus. This poison is easily ob- 

 tained by causing the diphtheria bacillus to grow 

 in common media in the laboratory for a while, 

 and the toxines develop in quantity ; then, by 

 proper filtration, the bacteria themselves can be 

 removed, leaving a pure solution of the toxic 

 poison. Small quantities of this poison are inocu- 

 lated into the horse at successive intervals. The 

 effect on the horse is the same as if the animal 

 had the disease. Its cells react and produce a 

 considerable quantity of the antitoxine which 

 remains in solution in the blood of the animal. 

 This is not theory, but demonstrated fact. The 

 blood of a horse so treated is found to have the 

 effect of neutralizing the diphtheria poison, al- 

 though the blood of the horse before such treat- 

 ment has no such effect. Thus there is developed 

 in the horse's blood a quantity of the antitoxine, 

 and now it may be used by physicians where 

 needed. If some of this horse's blood, properly 

 treated, be inoculated into the body of a person 

 who is suffering from diphtheria, its effect, pro- 

 vided the theory of antitoxines is true, will be to 

 counteract in part, at least, the poisons which are 

 being produced in the patient by the diphtheria 

 bacillus. This does not cure the disease nor in 

 itself drive off the bacilli, but it does protect the 

 body from the poisons to such an extent as to 

 enable it more readily to assert its own resisting 

 powers. 



This method of using antitoxines as a help in 

 curing disease is very recent, and we can not even 

 guess what may come of it. It has apparently 

 been successfully applied in diphtheria. It has 

 also been used in tetanus with slight success. 

 The same principle has been used in obtaining an 



