50 IMMUNE SERA 



other two sera, and the sera agglutinate the corpuscles 

 of Group 2, but not of Group i. 



An examination of this grouping shows that in no 

 case is there an agglutination of erythrocytes by their 

 own serum, in other words these are isoagglutinins but 

 not autoagglutinins. A somewhat different classification 

 was made by Jansky, and independently of him also by 

 Moss. Both these authors find it necessary to establish 

 four groups in order to embrace all the cases met with. 



Gay calls attention to the fact that the clumping of 

 erythrocytes by serum is not necessarily due to the pres- 

 ence of an agglutinin at all, but may be due to variations 

 in the molecular concentration of the serum constituents 

 or. of the constituents of the blood cells. 



The mere occurrence of these substances in blood 

 serum, to be sure, does not at all prove that isoag- 

 glutination or isohaemolysis of isoprecipitation occur 

 when such transfusions are done. In fact we do 

 not even know whether these substances exist at 

 all in the blood plasma. Nevertheless, until we 

 learn otherwise, it will be well to bear in mind the 

 possible danger from this source, and to undertake 

 no transfusions in which examination shows the 

 existence of homologous antibodies. 



Technique of Tests Preceding Transfusion. It 

 is evident that our tests must be reciprocal, i.e., 

 we must test the serum of both donor and recipient 

 against the blood corpuscles of the other. To do 

 this we collect part of the blood from each individual, 

 part in citrated salt solution and part in a plain test- 



