350 INFECTION AND IMMUNITY. 



von Dungern with the precipitins seem to show 

 that such intracellular overproduction actually 

 does occur. The experiments concern the fate of 

 "Majaplasma" (plasma of the spider-crab) when 

 injected into the circulation of the rabbit (see 

 above). If a single injection of the serum is 

 given, a specific precipitin for the latter body in 

 due time may be demonstrated in the serum of the 

 rabbit. Eventually the precipitin disappears from 

 the circulation by excretion or other means. At 

 that time, when all the precipitin has disappeared, 

 one may assume that the cells of the animal still 

 contain an increased number of precipitin recep- 

 tors, although the latter are no longer produced to 

 such an extent that they are thrown into the cir- 

 culation. If this condition exists the tissues of 

 the animal at this time should be able to absorb a 

 larger amount of the foreign serum, given in a sec- 

 ond injection, and perhaps absorb it more rapidly 

 than the tissues of an untreated rabbit. Using a 

 specific precipitating serum in order to detect 

 traces of the foreign serum which still remained in 

 the blood of the injected animal, von Dungern de- 

 termined that its tissues actually do absorb the 

 plasma more rapidly than do the tissues of the 

 untreated rabbit. The cells of the former have a 

 greater absorbing power, i. e., a greater binding 

 power for the plasma; therefore, an increased 

 number of receptors. 



These examples are, perhaps, sufficient to illus- 

 trate the principles of experimentation which have 

 been followed in the attempt to obtain definite 

 proof of the correctness of the essential points of 

 the theory. The results are in entire accord with 



