196 STUDIES IN IMMUNITY. 



is exhausted, becomes decolorized. Let us now take the same 

 amount of coloring fluid and a piece of filter paper of exactly the 

 same size as before. Instead of plunging this entire piece of paper 

 into the fluid we cut it up into pieces. When we place the first 

 piece of paper in the fluid it takes on a very dark shade and de- 

 prives the coloring fluid of a good deal of its color. We then add 

 a second fragment of paper, and, after another interval, a third. 

 These latter pieces take only a very faint tinge owing to the more 

 or less complete decolorization of the fluid. The fluid soon becomes 

 entirely decolorized and the last fragments added remain quite white. 

 By analogy we may consider that, in the first instance, when red 

 blood corpuscles are added in a single dose they become sus- 

 ceptible to a loss of hemoglobin, although they only " stain faintly" 

 with the active principles, but that in the latter conditions, when 

 added in divided doses, they absorb a much larger dose of these 

 substances and so exhaust the serum and prevent the destruction 

 of subsequently added corpuscles. 



It is difficult to understand just how alexin destroys sensitized 

 corpuscles and causes their hemoglobin to pass out. We may men- 

 tion a fact that may have some bearing on researches along this 

 line. We add defibrinated rabbit blood to a rather small dose of 

 hemotoxin and wait until hemolysis is complete. At the same time 

 we add a corresponding amount of normal guinea-pig serum to the 

 same amount of blood, in which case the corpuscles remain intact. 

 We then add to each mixture a large amount of distilled water, which 

 will destroy the corpuscles in the second mixture as well. We have 

 then two fluids; in the first the corpuscles have been destroyed by 

 active serum and in the second by distilled water. To each of these 

 fluids we then add sufficient salt to render them isotonic. In the 

 mixture in which the corpuscles were dissolved by distilled water 

 the stromata show energetic plasmolysis and retract. In the other 

 fluid containing hemotoxin the stromata keep their primitive 

 rounded form and apparently do not show any effect from the 

 increased concentration. It would seem as if the alexin from the 

 active serum had destroyed or digested something in the corpuscles 

 that has to do with the action of plasmolysis and phenomena of osmosis. 

 The diffusion of soluble hemoglobin would perhaps be the result of 

 such destruction. 



