STUDIES ON HAEMOLYSIS. 29 



blood-cells we had previously shown to be very sensitive to the iso- 

 lysin, several times with considerable quantities of serum A. As 

 a matter of fact an antibody was developed, so that 0.4 cc. of the 

 serum thus obtained were able to protect 1 cc. of a 5% sensitive 

 goat-blood-cell mixture against solution by isolysin A (0.5 cc.). The 

 blood-cells of this same goat No. 10, on the contrary, after they had 

 been repeatedly washed with physiological salt solution to free them 

 from serum, proved just as susceptible to the isolysin as before. 

 Hence it follows that the isolysin here concerned, isolysin A, causes 

 the production of antilysins in the body of the same species when 

 it finds fitting receptors. 



From this we conclude that the insensitiveness of the red blood-cells 

 can only be due to the lack of receptors for the isolysin. A further 

 conclusion must be that these receptors are not present in any other 

 tissue of buck A, that they are absent in the entire organism, for other- 

 wise there should have been a formation of anti-isolysin. 



It goes without saying that we repeated these experiments on 

 a large number of animals in order to exclude all accidental phenom- 

 ena. In the course of these experiments we noted numerous and 

 interesting variations in the reaction to isolysins. 



Of special interest is goat B, which had been treated exactly like 

 buck A. At first it seemed as though the experiment with this 

 animal would run an entirely different course, for during the first 

 fourteen days we were unable to detect even a suggestion of an iso- 

 lysin. The red cells, however, remained completely sensitive to the 

 isolysin derived from buck A. Then suddenly on the fifteenth day 

 after the blood injection a hsemolysin made its appearance, one 

 which acted on goat blood quite as strongly as the isolysin of buck 



A. The animal's own blood-cells were just as insensitive to this 

 haemolysin as were those in the first experiment to theirs. Here also, 

 then, we were dealing with an isolysin, not an autolysin. The sen- 

 sitiveness of the blood toward isolysin A continued. We now 

 examined the majority of our goats in order to determine their sen- 

 sitiveness to this isolysin, and found that some animals which were 

 highly sensitive to isolysin A w r ere very slightly sensitive to isolysin 



B, and vice versa. The blood of buck A occupied a peculiar place. 

 It was as completely insensitive to isolysin B as it was to that of 

 its own serum. 



From the behavior of the blood of the various animals toward 

 these two isolysins. it was clear that these isolysins were essentially 



