TOXIN AND ANTITOXIN. 



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 is 

 entirely dependent upon the reaction of the animal toward previous inocu- 

 lations. 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 Institute, 

 serves as an example of how such 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 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 first sinks and 

 then is followed by a compensatory rise. By becoming acquainted with the 

 wave-like fluctuations in the antitoxin content of the serum, and renewing 

 the injection at the time of highest content, one can produce a serum with 



