124 THE LTSINS. 



the gainea-pig serum of its hemolytic action, but had no effect upon 

 its agglutinating properties. The serum rendered inactive, so far as 

 its hemolytic properties are concerned, by heating, was found to re- 

 cover these properties on the addition of certain amounts of the 

 serum of either normal guinea-pigs or rabbits. The active serum 

 was found to be without effect upon the corpuscles of the guinea-pig 

 itself and upon those of the pigeon, but with slight action on the cor- 

 puscles of the rat and the mouse. The active serum from the 

 guinea-pig was found to be powerfully toxic when injected intra- 

 venously into the rabbit. These experiments made by Bordet dem- 

 onstrated the identity of the processes of bacteriolysis and hemolysis ; 

 and most of the subsequent investigation has been confined to a study 

 of the phenomenon as observed in the solution of blood corpuscles. 



Ehrlich and Morgenroth ' treated a goat at irregular intervals for 

 eight months with subcutaneous injections of defibrinated sheep's 

 blood diluted with 0.85 per cent, salt solution, until the mixture con- 

 tained only five per cent, of blood. The serum of this goat rapidly 

 dissolved the erythrocytes of the sheep in vitro ; while the serum of 

 a normal goat had but slight solvent action on the blood corpuscles 

 of the sheep. In this case agglutination did not precede hemolysis. 

 When the immune serum was heated for half an hour at 56°, it lost 

 its solvent action, but on the addition of the serum of a normal ani- 

 mal its activity was regained. The added serum was active when 

 obtained from either the goat or the sheep, but less so from the latter. 

 Normal serum was found to soon lose its power of restoring the 

 activity of heated immune serum and was effective only when freshly 

 obtained from the animal. These investigators agreed with Pfeiffer 

 that at least two substances must be present in the blood serum in 

 order to induce bacteriolysis or hemolysis. For the first, which is 

 thermo-stable, they retain the name proposed by Pfeiffer, of " immune 

 body " ; while for the second, which is thermo-labile, they substitute 

 for the "something" of Pfeiffer the term "addiment." It will be 

 understood that the thermo-stable or immune-body is unaltered by a 

 heat of 56°, while the thermo-labik substance, or addiment, is de- 

 stroyed at this temperature, but is also contained in normal serum ; 

 and this explains why the immune serum after being rendered in- 

 active by heat is regenerated by the addition of a small amount of 

 normal serum. It was at first supposed by Ehrlich that the immune 

 body is a substance which is brought into existence during the proc- 

 ess of immunizing the animal, while the addiment was supposed to 

 be present normally in the blood. Ehrlich's theory provided for a 

 combination between the immune body and the blood corpuscles ; 

 however, this does not lead to solution of the corpuscle until the 

 substance addiment is brought into the compound. The following 

 experiments furnish the basis of this theory: Tubes each containing 

 ^Berliner Uin. WocKenschrift, 1899. 



