TSE LYSINS. 127 



in their hemolytic action on sheep's blood, while their action on the 

 blood corpuscles of the guinea-pig and the rabbit was completely de- 

 stroyed. Indeed, heating for three hours at 56°, or heating the serum 

 diluted with an equal volume of water for one-half hour at 65°, had 

 no effect upon the hemolytic action on sheep's blood. This indicated 

 that the addiment in these sera differs from that observed in the 

 goat experimented upon in the first series, and the fact that heating 

 to 56° destroyed the action of these sera on the blood of the guinea- 

 pig and of the rabbit suggested that they contain at least two addi- 

 ments, one of which is necessary to the hemolytic action on the blood 

 of the guinea-pig and the rabbit and is destroyed at 56°, while the 

 other is that by virtue of which the hemolytic action on sheep's blood 

 results and which is not destroyed at a temperature of 56°. In other 

 words, there must be in these sera two addiments one of which is 

 thermo-stable, while the other is thermo-labile. 



In order to solve the problem presented by this new discovery, 

 Ehrlich and Morgenroth determined to separate the two components 

 in these sera. The immune body was easily obtained by combining 

 it with erythrocytes at 0° and it was found that when these sera were 

 treated with 10 per cent, of their volume of normal hydrochloric acid 

 and the mixture digested for from thirty to forty-five minutes at 37° 

 and neutralized, they lost their hemolytic effect on sheep's blood. 

 The acid destroyed the specific addiment in these sera, but had no 

 effect upon the immune body. The experiment was carried out as 

 follows : To five c.c. of the five per cent, sheep's blood dilution there 

 was added 0.15 c.c. of the immune serum rendered inactive with hy- 

 drochloric acid (it having been previously shown that this amount of 

 active serum was sufficient to produce complete hemolysis in five c.c. 

 of the blood dilution). After the mixture had stood for half an hour 

 at room temperature, it was centrifuged and separated into sediment 

 and supernatant fluid. To the sediment there was added two c.c. of 

 normal goat serum and to the supernatant fluid there was added 

 another portion of the diluted sheep's blood, and also two c.c. of nor- 

 mal goat serum. When thus treated the corpuscles in the sediment 

 were completely dissolved, while the supernatant fluid had no action 

 upon the erythrocytes which had been added, notwithstanding the 

 presence in it of the addiment. This showed that all of the immune 

 body was contained in the sediment. However, this experiment also 

 showed that the addiment needed to render the immune body active 

 is present in normal goat serum and indicates that there is in normal 

 serum a thermo-stable addiment ; but it was shown that the thermo- 

 stable addiment was not present in the sera of all goats. It was 

 concluded that in the serum of the goat used in the first experiment 

 and in the sera of the goats used in the second experiment the same 

 immune body was present, but that the serum of the first immunized 

 goat contained only thermo-labile addiment, while those of the two 



