NEUTRALISATION OF TOXIN 161 



the actual volume of serum injected. The anti-serum may be 

 regarded as a solution containing a variable amount of the anti- 

 toxic or anti-microbic constituent, and for therapeutic use its 

 strength must be ascertained, and is for convenience described in 

 arbitrary unite. 



The dose of antitoxin is dependent upon the gravity of the 

 disease, and not on the age of the patient, for evidently just as 

 much toxin may be formed in a child as in an adult. The anti- 

 toxins are strictly specific ; diphtheria antitoxin, for example, has 

 not the slightest influence in tetanus. 



To obtain an immediate reaction to antitoxin it should be 

 administered intra-venously. A subcutaneous injection may not 

 be completely absorbed in less than thirty-six hours, an intra- 

 muscular injection is much more rapidly absorbed. 



In cases of mixed infection, e.g. where diphtheria bacilli are 

 associated with streptococci or staphylococci, the diphtheria anti- 

 toxin will have no influence on the streptococcic or staphylococcic 

 infection. 



The complications and accidents of antitoxin treatment are few 

 and usually unimportant. Abscess and other local troubles at the 

 seat of inoculation should not occur if proper antiseptic precautions 

 be taken. Urticaria or other rashes and joint pains are by far the 

 most troublesome complications. These are due to the injection 

 of foreign serum, and not to the antitoxin, for the serum of an 

 untreated horse produces a like effect. Repeated injections of 

 serum at short intervals may be continued for a long period without 

 inducing more disturbance than that caused by one or two or a few 

 injections, but if twelve days or more elapse between two injections 

 a condition of " supersensitation," due to anaphylaxis, ensues 

 (see p. 168). This consists in the rapid appearance of rashes, joint 

 pains, pyrexia, etc., or even of grave symptoms, faintness, vomiting, 

 dyspnoea, convulsions, collapse, etc. 



Anti-sera may be used as prophylactics, but the immunity 

 produced by them does not last more than three weeks. 



Various hypotheses have been advanced to explain 

 the manner in which toxin is neutralised by antitoxin. 

 Roux and Buchner suggested that the antitoxin in 

 some way renders the cells and tissues insusceptible 

 to the toxin, and Buchner performed experiments show- 

 ing that while mice are more susceptible than guinea- 

 pigs to tetanus toxin, a tetanus toxin-antitoxin mixture 



IT 



