22 LECTURES ON IMMUNITY 



animal of another species and found that the serum from 

 this second animal contained a substance, called lacto- 

 serum, which gave a precipitate with the casein of the 

 injected milk. P. T. M tiller, 1 who investigated the prop- 

 erties of this lactoserum, found that it entered into a com- 

 pound with the casein of the milk, which compound was 

 precipitated in the presence of calcium-salts. Now the 

 lactoserum is decomposed by heating to a temperature of 

 70 to 71 for thirty minutes. By heating the precipitate 

 which contained the lactoserum combined with casein, in a 

 solution of NaCl, to 100 C, Miiller succeeded in recov- 

 ering the casein without loss. Evidently the precipitate 

 is a little soluble, and the Dissolved precipitate is partially 

 dissociated into its components. Through the high tem- 

 perature the free lactoserum is destroyed, then new 

 quantities of the precipitate are dissolved, and the process 

 goes on until all the lactoserum is decomposed and the 

 casein dissolved and recovered. 



There are other methods of destroying one of the com- 

 ponents in an innocuous mixture of a toxin and its anti- 

 body. Different chemical agents may destroy the one of 

 these substances more rapidly than the other. Thus ricin 

 is digested by proteolytic ferment, but to a much smaller 

 extent than its antibody. This behaviour was used by 

 Danysz 2 for restoring the poisonous effect of ricin which 

 had been mixed with so much antiricin that the resulting 

 fluid was innocuous. This fluid was mixed with a solution 

 of ferment and left for a sufficient time (e.g. twenty-four 



1 P. T. Miiller: Archiv f. Hygiene, 44. 150 (1902). 



2 Danysz : " Melanges des toxines avec les antitoxines," Ann. de Vlnst. Pas- 

 teur, 16. 311 (1902). 



