276 LECTURES ON IMMUNITY 



less than the probable error ; only in two do they exceed 

 these, and even then not greatly. The agreement may be 

 regarded as striking, and the whole series, which is the 

 condensed result of about seven hundred and fifty tests, 

 of every mixture there were taken six to eight different 

 tests in as many test-tubes, may be regarded as a model 

 for further investigation on these difficult subjects. 



The concordance of ^- calc . with g obtm may serve as a very 

 strong proof that the equation used for the calculation is 

 the correct expression of the phenomenon. 



As has already been noted (cf. p. 3), Hammarsten and 

 Roden 1 observed that normal horse-serum contains a sub- 

 stance which is in many respects similar to antirennet. 

 Therefore Madsen and Walbum have examined this anti- 

 body in a similar manner, only the time of reaction between 

 the two antibodies was longer, two to four hours. The 

 results of experiments with two different preparations are 

 abridged in the table on opposite page. 



This process of neutralisation is not reproduced by the 

 formula valid for the action of rennet upon antirennet, 

 but the equation is the same as that valid for the neutral- 

 isation of tetanolysin by means of cholesterin, which 

 indicates that one molecule of rennet and one of the 

 antibody give only one molecule of the reaction-product. 

 The constants are, if we use as unit concentration that 

 of the unneutralised rennet in the first experiment, for the 

 first preparation K 0.354, an d for the second K 0.138 ; 



1 Roden: Upsala lakareforenings forhandlingar, 22. 546 (1887). Roden 

 observed that serum of swine blood is nearly as active as that of horse blood; 

 sera from cattle or rabbits have a much weaker action. Even ascites-fluid 

 has some action. The active substance is destroyed by heating for some few 

 minutes to 70 C. or even by treatment with alcohol. 



