ALEXIN ABSORPTION. 399 



that have not always been as carefully considered as they should 

 have been. One of these influences, which we wish to consider in 

 particular, is the amount of normal salt solution that is used in the 

 mixtures. Variations in this factor are evident in many experi- 

 ments on hemolysis, and such variations, we believe, explain certain 

 phenomena that have been noted by Pfeiffer and Friedberger and 

 by Sachs, to which they have referred as the antagonistic property 

 of normal sera. Sachs offers a rather complicated explanation of 

 this property, which, as we shall later see, appears to us incorrect. 



When fresh normal serum (alexin) is mixed with a suitable sen- 

 sitizing serum (heated to 55 degrees) and the substance under 

 consideration, usually red blood cells or bacteria, to determine alexin 

 fixation, the cells employed are usually added as a suspension in 

 salt solution. The amount of this solution, however, varies; in 

 dealing with red blood corpuscles many workers use a considerable 

 dilution, for example, a 5 per cent suspension, and a relatively large 

 volume of this suspension is therefore employed. 



It has frequently been noted by experimenters that hemolysis 

 in salt solution is very rapid. A given quantity of corpuscles is 

 generally hemolyzed much more rapidly by a given dose of alexin 

 and sensitizer when the liquid that serves as a medium is salt 

 solution than when it is normal, and supposedly inert, heated 

 serum.* On comparing normal inert serum with salt solution, we 

 find that the latter favors hemolysis, or, more correctly speaking, 

 that the normal serum inhibits hemolysis; it is to be noted that 

 this difference is very marked only when the corpuscles are not 

 strongly sensitized. To what is the antagonistic effect due? As 

 both Pfeiffer and Friedberger (bacteriolysis) and Sachs have shown, 

 the normal serum does not act by weakening the sensitization ; nor 

 directly on the corpuscles or the bacteria. We shall presently 

 consider Sachs' explanation, which supposes that the serum owes 

 its inhibiting effect to the presence of normal amboceptors that 



* Muller (Central, fur Bakt., XXX, 1901) was, we believe, the first to note this 

 fact in particular. It has been more recently considered by other investigators, 

 and in particular by Muir and Browning (Jour, of Hygiene, VI, 1906), and by 

 Liebermann and Fenivessy (Peters. Me"dic. Chirug. Pressen, 1907), etc. We have 

 already mentioned (see p. 383.) Klein's researches and our own on horse serum, 

 in which it was shown that alexin is better absorbed by corpuscles when salt 

 solution is present. 



