114 The Nature of Precipitin Beactions 



cipitiim not being materially altered, although deposits formed badly 

 at 0°. Reactions appeared to occur most rapidly at 35°. Working with 

 bacterioprecipitins Kraus (1897) kept his tubes at 37°, and Nicolle 

 (1898, p. 162) and Radziewsky (1900, p. 434) found this the best 

 temperature for the reaction. Kister and Wolff (18, xi. 1902) state 

 however that there is no special difference in the reaction at room 

 temperature and at 37° C, this being contrary to the experience of 

 all other workers. 



Observations made in this laboratory by Mr Strangeways have 

 finally disposed of the question. Blood dilutions and antisera were 

 placed at 37°, at about 12°, and in the ice-chest at about 5° C. prior 

 to being mixed. After having attained the temperature of their 

 surroundings, the antisera were added to the blood solutions, and the 

 time noted when reaction took place, and it was found that a low 

 temperature markedly retarded the reaction, although it had no influence 

 upon the amount of precipitum as measured by my volumetric method. 



The statement therefore of Kister and Wolff is wrong. It can 

 doubtless be explained in a measure by the fact that in routine work 

 with powerful antisera, the reaction begins almost immediately even at 

 low temperatures. 



The effect of Heat upon Precipitating Antisera. 



The following table contains the results of experiments by different 

 observers with regard to the effects of various temperatures upon 

 antisera obtained from rabbits. The antisera were tested, after heating, 

 upon their homologous bloods with which they had previously given 

 reactions. Some authors state the time of exposure, others not. 



Linossier and Lemoine (21, ill. 1902) state that their anti-horse 

 serum, which had acted on horse blood in the dilution 3 : 100 before 

 heating, was exposed for 48 hours at a temperature of 60° C. At the 

 end of that time a coagulum had formed, and on separating the clear 

 fluid therefrom it was found to cloud a 10 : 100 horse blood dilution. 

 Diluted five times in saline, the antiserum showed a still greater 

 resistance to heat, for after 48 hours at 60° it showed no loss of strength. 

 After four days at 60° it still precipitated a 10 : 100 solution. 



It will be seen that the Bacterioprecipitins are much more readily 

 destroyed by heat than are the others, a fact which has been brought 

 forward as a reason for considering them antibodies of another nature. 



