PROPERTIES OF ANTTSENSITIZERS, 285 



species A with the serum of normal untreated animals of species B 

 capable of neutralizing the specific sensitizers formed by species 

 B against such cells as red blood corpuscles? Experimentally, we 

 learn that it is; for our antiserum, which, as already shown, is 

 actively antisensitizing, was obtained from guinea-pigs that had 

 received only normal rabbit serum. The same results are true if 

 we replace the sensitized ox blood by hen or human blood, each 

 sensitized by its respective hemolytic serum from the rabbit (rabbit 

 > hen, 56 degrees, or rabbit > human, 56 degrees). This agrees 

 very well with the findings of various writers and particularly with 

 those of Ford.* This writer, having found that hen corpuscles are 

 agglutinated, not only by the serum of a rabbit immunized with 

 hen blood, but also to a certain extent by normal rabbit serum, 

 injected hens, on the one hand, with normal rabbit serum, and on 

 the other with the specific serum of rabbits that had been immunized 

 against hen blood (rabbit > hen serum). He found that either 

 antiserum from the hen neutralized both the specific agglutinin 

 of rabbit > hen serum and the normal agglutinin of normal rabbit 

 serum. Pfeiffer and Friedbergerj obtained analogous results with 

 antisera for bacteria. 



We may conclude, then, from these results that as a general rule 

 antiserum obtained by injecting the normal serum of species A, and 

 acting, therefore, on the normal antibodies, will also neutralize the 

 various specific antibodies formed by A in response to immunization. 



(B) Is the antisensitizer used up in producing its effect as are 

 the other antibodies already studied? In other words, is not the 

 amount of sensitizer that an antiserum can neutralize, limited? 

 It is almost superfluous to add that this turns out to be true ; there 

 is a minimal dose of antiserum, a less amount than which fails to 

 protect sensitized corpuscles. And, moreover, it may be shown 

 that the addition of a sufficient amount of washed sensitized bovine 

 corpuscles to antiserum deprives it of its antisensitizing property, 

 as is shown on adding additional sensitized corpuscles to such 

 treated antiserum .% Of course antiserum treated with the same 



* Zeit. fur Hygiene XL, 1902, 363. 



t Berliner klin. Woch., 1902, No. 1, and Centralblatt fiir Bakt., XXXIV, 

 1903, 74. 



| We shall consider this experiment in detail in another connection. 



