PROPERTIES OF ANTISENSITIZERS. 309 



afforded by the injection of an alien serum should be attributed, as 

 a rule, to the secretion of antagonistic substances. The fact that 

 this substance is not easily detectable experimentally is due to its 

 inhibition by certain of the conditions to which reference has been 

 made. Such conditions depend on the doses used and the relations 

 of affinity between the substances that take part in the reaction. 

 In so far as dosage is concerned, it should be noted that the amount 

 of immune serum administered for passive immunity is very small 

 in proportion to the volume of blood in the recipient; under such 

 conditions the antagonistic power that soon develops has greater 

 chance to manifest itself than in test-tube experiments, where the 

 tendency is to minimize the amount of antiserum. 



Conclusions. 



The study of an antiserum obtained by injecting animals of species 

 A with the normal serum of species B gives rise to the following 

 remarks : 



I. Various red blood cells, sensitized each by its appropriate 

 heated hemolytic serum obtained from an animal of species B, 

 lose their sensitization to alexin when treated with the antiserum. 

 The sensitization is generally diminished rather than completely 

 abolished; it may, indeed, frequently be demonstrated when the 

 corpuscles are placed in a medium which tends to diminish their 

 resistance, for example in salt solution. 



II. It is not necessary in obtaining an antiserum that neu- 

 tralizes various specific sensitizers, obtained in each instance from 

 an animal of species B, to inject animals with the respective specific 

 sensitizers, but simply with normal serum from species B. 



III. The power of this antiserum to neutralize various specific 

 sensitizers as well as the normal antibodies (or sensitizers) in B 

 serum may be attributed to the presence in this antiserum of a 

 single antisensitizer. There is no need of assuming the existence 

 of a multiplicity of antisensitizers. As far as the action of anti- 

 sensitizer is concerned, there is a closer relation between sensitizers 

 from the same source acting on different cells than between sen- 

 sitizers from different sources acting on the same cell. 



IV. The antisensitizer is used up in acting. The addition of sen- 



