TOXIN AND ANTITOXIN 



even completely fail to do so, not that the latter are not actively immunized, for 

 they are, but because they contain very little antitoxin within their serum. 



It is impossible to recommend a distinct scheme for the immunization 

 of a horse. The intervals between the injections and the size of the dose 

 are varied according to the reaction of the animal toward previous 

 inoculations. A good rule to follow is, that a fresh injection should be 

 given only if the reaction from the preceding one has entirely subsided. The 

 reactions are both local and general. The local reaction comes in the form 

 of edema, infiltration, and sterile abscesses; the general, loss in weight 

 and appetite and increase in temperature. 



The following chart of Salomonsen and Madsen, of the Copenhagen Serum Insti- 

 tute, serves as an example how a diphtheria serum is produced. A gravid mare 665 kg. 

 in weight was selected and injections were given as follows. 



The time selected for venesection is important. Antitoxins like any 

 other antibodies do not arise immediately after an injection, but only after 

 a certain incubation period. The amount of antitoxin at first gradually 

 increases, then begins to sink, and after that remains constant for a certain 

 period until it finally disappears. If at a time when the serum contains a 

 certain amount of antitoxin a new inoculation is undertaken, the so-called 

 "negative phase" sets in, i.e., the amount of antitoxin within the serum 

 sinks. It is followed by a compensatory rise, "positive phase." By 

 becoming acquainted with the wave-like fluctuations in the antitoxin con- 

 tent of the serum, and renewing the injection at the time of highest content, 

 one can produce a serum with very strong antitoxic qualities. This 





