XLI. A GENERAL REVIEW OF THE RECENT WORK 



IN IMMUNITY. 1 



By PAUL EHRLICH. 



Two years have elapsed since the appearance of my "Collected 

 Studies in Immunity" in Germany, and now that the book is about 

 to appear on the other side of the ocean it is a pleasure for me to 

 review briefly the progress made in that time, naturally without 

 pretending to give a complete resume of the literature. 



I may at once say, however, that very little really new has been 

 added to the views formulated by myself and my collaborators, and 

 that the stereochemical conception of the immunity reaction, despite 

 numerous attacks, has proven itself able to dominate every phase of 

 the subject. 



The arithmetical view of the toxin-antitoxin reactions and their 

 analogues, which was introduced chiefly by Arrhenius and Madsen, 

 has invariably shown itself to be untenable. It has led to a numer- 

 ical science which is far removed from the principles of biological 

 investigations and from the experimental results underlying these. 

 On the other hand, so able an authority as Nernst at once recognized 

 that the laws of chemical equilibrium are not applicable to mixtures 

 of toxin and antitoxin. In addition to this von Dungern, Morgen- 

 roth, and Sachs have collected considerable new experimental evi- 

 dence which demonstrates absolutely that the toxin-antitoxin 

 combination gradually becomes firm, although it may in some 

 instances be quite loose in the first stage. The complex constitution 

 of the poison solutions has thus been conclusively demonstrated; 

 and I may also remind the reader that there can also no longer be 

 any question as to the independent existence of toxons in diphtheria 

 poison, for van Calcar has succeeded in a direct separation of these 

 bodies. 2 



1 This chapter is written expressly for this American edition. 



2 van Calcar effected this by means of an ingenious dialyzing procedure 

 (Berlin, klin. Wochenschr. No. 39, 1904). Certain objections raised by Romer 



577 



