THE PHENOMENA OF ADSORPTION. 453 



a serum is easily obtained, and the experiments which have been 

 outlined confirm Bordet and Gay's opinion entirely. 



We know that the fixation of alexin on corpuscles is very markedly 

 favored by the addition of normal salt solution; this fact is very 

 evident in the case of horse serum. Klein was first to note that 

 guinea-pig corpuscles mixed with fresh and undiluted horse serum 

 fix little alexin, although they absorb it completely when a con- 

 siderable amount of salt solution is added. The sensitizer, on 

 the contrary, is well absorbed even when the serum is concentrated. 

 Consequently, if we treat undiluted horse serum with an equal 

 volume of washed guinea-pig corpuscles, we shall obtain a fluid 

 which is rich in alexin but is deprived of sensitizer. 



We find that such a serum produces the following effect: 

 (a) When mixed with intact heated bovine serum and guinea- 

 pig corpuscles it produces the phenomenon of conglutination and 

 hemolysis very clearly. This fact proves that the bovine sensi- 

 tizer is the one which acts, as no other one is present. 



(6) When mixed with heated bovine serum that has been pre- 

 viously treated with guinea-pig corpuscles it produces no phe- 

 nomenon. This proves that such a mixture contains no sensitizer 

 at all, and consequently condemns Ehrlich and Sachs' thesis, in 

 accordance with which the bovine sensitizer should still be present. 

 In control tubes, of course, it is proved that such heated bovine 

 serum, when mixed with untreated horse serum, gives the phe- 

 nomenon perfectly, in which case, of course, the sensitizer that 

 acts is in the horse serum. 



(c) When mixed with heated bovine serum that has been 

 deprived of its amboceptor by contact with guinea-pig corpuscles 

 this horse serum deprived of its sensitizer still gives the phenomenon 

 if the corpuscles added are not normal, but have first been sensi- 

 tized by contact with heated bovine serum and subsequently 

 washed. This completes the demonstration of the previous experi- 

 ment on the fixation of the bovine sensitizer by corpuscles in 

 absence of alexin. The experimental details of these experiments 

 follow. Materials are prepared as follows: 



I. Fresh horse serum containing alexin but deprived of sensi- 

 tizer. 2 c.c. of washed guinea-pig blood is added to 2 c.c. of horse 

 serum. After contact for quarter of an hour the mixture is cen- 



