154 Tests with Precipitins 



animals were treated with culture-filtrates, both dialyzed and non- 

 dialyzed, precipitating and agglutinating antisera were also obtained. 

 In confirmation of Kraus (see above), he was unable to obtain precipitins 

 for B. diphtheriae. 



There is fairly general agreement that the bacterioprecipitins and 

 agglutinins are distinct chemically. I have noted above that both may 

 coexist in a serum, and will refer the reader to p. 50, where the differ- 

 ences between agglutinins and precipitins are more especially discussed. 

 Kraus and von Pirquet (5, vii. 1902) found that bacterial culture- 

 filtrates contain not only a precipitable substance, but also specific anti- 

 agglutinin, the latter being probably identical, they think, with the 

 agglutinatable substance of bacteria. Pick (1902, p. 54) considers 

 the precipitable substances in old and fresh culture-filtrates to be 

 differently constituted, as they combine differently with bacterio- 

 precipitins. The precipitable substance in old typhoid cultures, 

 according to Pick, is not albumose, nor probably peptone, nor nucleo- 

 proteid, and it is not an albuminous body. The reader is referred to 

 Pick's third communication (1902) for details regarding the effects of 

 various chemical agents upon bacterioprecipitins. 



According to Pick (1902, p. 81), typhoid bacterioprecipitins are 

 inactivated by an exposure of 30 45 minutes to 58 60 C., but not 

 the agglutinins. The inactivated serum prevents the action of fresh 

 antiserum. He considers (p. 92) that the inactivated serum acts upon 

 the precipitin, not upon the precipitable substance (compare p. 91). 

 As Rostoski (1902, b, p. 23) points out, the temperature at which 

 bacterioprecipitins are inactivated is lower than that at which 

 haematoprecipitins etc. are inactivated, and this indicates that they 

 may be of a different nature. He suggests that the name " coagulin " 

 should perhaps be retained for bacterioprecipitins so as to distinguish 

 them from the precipitins which act upon blood and the like. This 

 term, coagulin, is rarely used. It was applied by Ehrlich (1900, Croonian 

 Lect.) and is used by Pick and a few others, but in my opinion it should 

 be dropped, as it will only lead to a confusion with the coagulins for 

 blood (see anticoagulins, p. 17) to which the term properly applies. 



Yeast-Precipitins. 



Schiitze (6, XI. 1902, p. 805) sought to discover if it were possible 

 by the use of precipitins to distinguish between different yeasts, which 

 were severally used for the immunization of rabbits. He cites an 



