Preface to the First Edition. 



lx my text-book on Physiological Chemistry, pub- 

 lished in 1906, I made an attempt to harmonize 

 the defensive measures, adopted by the animal 

 organism against products generated by cells out of 

 harmony with the body, with the metabolic processes 

 of the individual cells of the body. I was of the 

 opinion that, when an invasion takes place of cells 

 which are out of harmony with the bodv. the blood 



j j ' 



or plasma, and the cells, the cells of the body respond 

 with counter-measures which are not entirely new to 

 the cells of the particular organ or of the blood ; on 

 the contrarv, I tried to bring the whole question of 

 the so-called reactions of immunity into close line 

 with processes that are normal, and consequentlv 

 familiar, to the cells. From the point of view stated 

 in the above-mentioned text-book, I attacked 

 experimentally the problem of the method of 

 defence, used by the animal organism, against the 

 invasion of substances out of harmony with the body, 

 the blood plasma, and the cells. In the first place 

 I studied the question whether normal blood plasma 

 contains definite ferments; and, in the second place, 

 whether the introduction of disharmonious substances 

 is followed by the appearance of ferments which were 

 not there before. I found, in fact, that, after the 



