xiv PREFACE TO THE FIRST EDITION 



introduction of substances out of harmony with the 

 blood plasma, ferments appeared which are capable of 

 transforming these products, and of depriving them 

 thus of their specific character. These facts estab- 

 lished beyond doubt one means of defence possessed 

 by the animal organism against the invasion of 

 disharmonious substances. 



My thoughts then turned at once to the relation 

 of these facts to immunity, and especially also to 

 anaphylaxy, and I undertook experiments to decide 

 the question as to whether the animal organism 

 develops any ferments of a specific nature against 

 substances produced by micro-organisms. And I 

 w^as particularly interested in the question whether 

 the stages that arise, in any given case, during the 

 decomposition of a particular substrate vary with the 

 species of the invading cell, and whether this may 

 not give us the explanation of many phenomena that 

 appear in the course of certain infections. Finally, 

 I was able to demonstrate that, during pregnancy 

 also, the organism defends itself, by means of 

 ferments, against certain constituents which are 

 passed into the blood, most probably from the cells 

 of the chorionic villi, and which, though in harmonv 



o * 



with the species, are out of harmony with the plasma. 

 This observation renders possible a diagnosis of 

 pregnancy. 



The above statements have a bearing on a great 



