336 STUDIES IN IMMUNITY. 



A similar and yet more striking example of the effect of a great 

 excess of isotonic solution will be given later. To retain the use- 

 fulness of the 5 per cent suspension and to obviate its errors, I have 

 employed this method of centrifugalizing the suspension in the 

 actual experimental tube, removing the supernatant fluid, and 

 subsequently adding the small amount of physiological solution 

 necessary to bring the blood suspension to its primitive volume. 



Another source of possible error in experiments of this nature 

 is the presence of anti-alexic action in the excess of heated immune 

 serum, which, in rare instances, inhibits the activity of the proper 

 alexin of the corpuscles. The occurrence of such an action is not 

 surprising when we consider that the usual procedure for the pro- 

 duction of an immune serum is to immunize animals with the whole 

 defibrinated blood, that is, with corpuscles plus serum. The remedy, 

 of course, consists in removing the excess of immune serum after 

 it has been allowed to come in contact with the corpuscles. 



Although the amount of rabbit alexin necessary to hemolyze 

 sensitized rabbit corpuscles is relatively large, it is easy to show 

 that smaller doses combine perfectly with the corpuscle-immune 

 body complex. As Muir expresses it, the combining power is per- 

 fect although the toxic power is slight. Such variations in toxicity 

 were previously noted by Bordet * in consonance with his quanti- 

 tative idea of the difference in alexins. 



If we take Table I, for example, and add to each of the super- 

 natant fluids of tubes 1 to 5, in which more or less hemolysis has 

 occurred, sensitized ox corpuscles (ox corpuscles, 0.025 of a cubic 

 centimeter + S. rabbit > ox, 55 degrees, 0.05 of a cubic centimeter), 

 we obtain no trace of hemolysis in any tube, which shows that the 

 rabbit alexin has already combined perfectly with the sensitized 

 rabbit corpuscles. 



Before proceeding to the proof of the simple nature of the guinea- 

 pig-rabbit immune body, it will be necessary to describe an experi- 

 ment which offers a valuable technical method for the solution of 

 this problem, and which may also prove of service in other hemolytic 

 experiments. It is already known that when corpuscles have been 

 hemolyzed by means of a heated specific serum, and a dose of 

 alexin, which is not in excess, added, the resulting stromata have 



* Bordet, see p. 234. 



