284 LECTURES ON IMMUNITY 



acquires the peculiar property of hindering the precipita- 

 tion of casein by means of lacto-serum. In the same 

 manner Eisenberg found that his precipitin for egg-albu- 

 men on heating for one hour to 72 C. was transformed 

 into an antiprecipitin. In the same manner the precipi- 

 tins against cholera and typhoid, prepared by injection of 

 cultures of the corresponding bacteria into the veins of a 

 horse, lose their property of coagulating the correspond- 

 ing bacterium on being heated for thirty minutes to about 

 60 C., 1 and acquire anticoagulating properties on heating 

 to 73 C. (for cholera-serum). Even for the agglutinins, 

 similar observations have been made by Eisenberg and 

 Volk. Through different experiments Miiller was led to 

 the conclusion that the antiprecipitin binds the casein, 

 with which it gives a compound soluble in the presence of 

 calcium salts. Antiprecipitin may even dissolve the pre- 

 cipitate, in the same manner as a carbonate is dissolved by 

 a not too weak acid. This was shown in a simple manner 

 by Eisenberg, by preparing in one test a mixture of pre- 

 cipitin and antiprecipitin with egg-albumen, and in a 

 second test a mixture of antiprecipitin and egg-albumen 

 with precipitin. In the second case no precipitate was 

 formed because the egg-albumen was bound by the anti- 

 precipitin, while in the first case precipitation occurred. 

 (The velocity of reaction is evidently rather slow, otherwise 

 the two experiments would give the same result.) Similar 

 experiments were made by Eisenberg with coagulating 

 serum antagonistic to the bouillon of typhoid cultures. 

 The antiprecipitins are derived from the precipitins, for 

 after these have been precipitated from the serum (for 



1 Pick: Hofmeisters Beitragc, 1. 8 1 (1901). 



