PARASITES 435 



the fact that his body is all the time producing more and 

 more of the antitoxine which neutralizes the toxine when it is 

 injected. After the period of toxine treatment which lasts 

 usually about six weeks, the horse is given about two weeks 

 rest to make sure of the neutralization of all the last dose of 

 toxine. Next, the horse is bled from the jugular vein in the 

 neck and as much blood is taken as the horse can well stand. 

 The blood is taken in a manner to insure its freedom from 

 bacteria of any kind and is allowed to stand until it clots, or 

 until the serum separates from the corpuscles. The serum 

 contains the antitoxine in solution. The serum is now drained 

 off from the clot, carefully tested as to its freedom from 

 bacteria, and standardized as to its strength in antitoxine. 

 It is now put up in small tubes to which sterilized needles for 

 injection may be attached and is ready for use. 



505. Curative Value of the Antitoxine. The curative value 

 of the antitoxine lies in its power to neutralize or destroy the 

 toxine and thus prevent the latter from attacking the tissues of 

 the body. The antitoxine also seems to be detrimental to the 

 development of the organisms at the seat of infection; therefore 

 by repeated doses the patient usually soon begins to improve 

 rapidly and the white patch begins to disappear from the 

 throat. It happens that neither the horse serum nor the anti- 

 toxine which it holds in solution are in any way harmful to the 

 human body, and so almost any quantity of the serum may be 

 injected. In ordinary practice, 3000 or 4000 units of anti- 

 toxine are given as a dose in cases of moderate severity, but in 

 cases of great severity or in cases which are far advanced when 

 a physician is called, as many as 8000 to 10,000 units are 

 given as a dose. 



506. Results of the Use of Diphtheria Antitoxine. Ever 

 since the early nineties of the last century, the horse serum for 

 the treatment of diphtheria has been in common use through- 

 out the civilized world and its effect on the death rate from this 

 disease has been remarkable. This is shown by the following 

 table which shows the average death rates, from diphtheria, 



