260 BACTERIA 



word. The chief examples are to be found in diphtheria, 

 tetanus, streptococcus, and pneumococcus. 



To be of value, antitoxins must be used as early as pos- 

 sible, before tissue change has occurred and before the 

 toxins have, so to speak, got the upper hand. When the 

 toxins are in the ascendency the patient suffers more and 

 more acutely, and may succumb before there has been time 

 for the formation in his own body of the antitoxins. If he 

 can be tided over the " crisis," theoretically all will be well, 

 because then his own antitoxin will eventually gain the 

 upper hand. But in the meantime, before that condition 

 of affairs, the only way is to inject antitoxins prepared in 

 some animal's tissues whose disease began at an earlier date, 

 and thus add antitoxins to the blood of our patient, early 

 in the disease, and the earlier the better, for, however soon 

 this is done, it is obvious that the toxins begin their work 

 earlier still. It should not be necessary to add that general 

 treatment must also be continued, and indeed local germ- 

 icidal treatment, e.g., of the throat in diphtheria and the 

 poisoned wound in tetanus. Further, in a mixed infection, 

 as in glandular abscesses with diphtheria, it must be borne 

 in mind that the antitoxin is specific and may therefore 

 probably fail in such mixed cases. 



After these preliminary remarks we will now consider 

 shortly some of the methods employed for the production 

 of antitoxins. An animal is required from whose body a 

 considerable quantity of blood can be drawn without injur- 

 ious effect. Moreover, it must be an animal that can stand 

 an attack of such diseases as diphtheria and tetanus. Such 

 an animal is the horse. Now, by injecting into the horse 

 (a) living organisms of the specific disease, but in non-fatal 

 doses, or (b) dead cultures, or (c) filtered cultures containing 

 no bacteria and only the toxins, we are able to produce in 

 the blood of the horse first the toxins and then the antitoxins 

 of the disease in question. The non-poisonous doses of 



