SPECIFICITY OF DEFENSIVE FERMENTS 97 



to the conclusion that they would do so, because it 

 had been noticed that, after the introduction of dis- 

 harmonious substances into the circulation, not only 

 do ferments appear which reduce the particular com- 

 pound inoculated, but the defensive ferments pro- 

 duced attack many other substances of the same order. 

 There was no production of strictly specific ferments, 

 but only of those which are limited in their action 

 to a particular class of compounds. And when sub- 

 stances that were in harmony with the body, but not 

 with the plasma, were chosen for these experiments, 

 no ferments appeared that were strictly specific. 



We tested the sera of tuberculous individuals, of 

 sufferers from carcinoma, of persons with salpingitis, 

 and others, for their behaviour towards placental 

 tissue, but in not a single case did decomposition 

 take place. To our great surprise it appeared, that 

 the animal organism onlv sets free strictly specific fer- 

 ments, when particular cells are themselves giving off 

 substances which are not in harmony with the plasma. 



How can we explain this different mode of 

 behaviour, according to whether we introduce 

 such disharmonious substances, or whether the 

 organism itself supplies them? There are various 

 possibilities to be considered. In the first place 

 the cell may give off the substances in question 

 only in minute quantities, a condition which we are 

 unable to imitate. Our methods of interference are 

 7 



