ALEXIN ABSORPTION. 407 



Similar instances have been met with in the studies on whooping- 

 cough made by one of us with Gengou. The sera of three children — 

 a brother and two sisters — suffering from the disease were tested 

 on the same day and in the same amounts ; as a general thing we 

 used highly sensitized corpuscles to test for alexin fixation. In the 

 control containing normal human serum, alexin and bacteria, 

 hemolysis appeared in a few minutes ; it took one-half hour and one 

 hour respectively in tubes containing sera of two of the children; with 

 the third serum there was no hemolysis. The three whooping-cough 

 sera, then, were unequally active, and it was found that the most 

 active came from the child that first fell ill and was then convales- 

 cent, while the weakest was from the one that was last taken with 

 the disease and still showed marked symptoms. The result is quite 

 natural, but if the sensitizing power were only moderate even in 

 recovered children one might wrongfully be led to the conclusion 

 that the alexin that affects the whooping-cough bacillus differs from 

 the hemolytic alexin. 



As a matter of fact the method is very exact only in the demon- 

 stration of powerful sensitizers,* and is not applicable for the ac- 

 curate titration of the activity of antimicrobial sera, or, at least, 

 cannot be compared in exactitude to Ehrlich's methods employed 

 in measuring the potency of antitoxins. 



And indeed the originators of the method recommended it 

 rather for the qualitative study of sera than for a quantitative 

 evaluation of their activity. 



* * 



The researches of Pfeiffer and Friedberger f and of Sachs $ con- 

 cerning the antagonistic properties (antibacteriolytic or antihe- 

 molytic) of normal sera may now be considered. 



A few data in hemolysis will simplify the matter in hand. A 



* It is not surprising, then, that in Moreschi's experiments (Berlin, klin. Woch., 

 1906, p. 1244) the method failed to demonstrate sensitizing properties in the 

 serum of a man who had received a single injection of killed tyhoid bacilli a few 

 days previously. 



t Pfeiffer and Friedberger, Deutsche med. Woch., 1905, Nos. 1 and 29; Cen- 

 tralblatt f. Bakt., XLI, 1906. 



X Sachs, Deutsche medicin. Wochen., 1905, No. 18; Centralblatt f. Bakt., 

 XL, 1906. • 



