DEFENSIVE FERMENTS OF THE ANIMAL ORGANISM 45 



have cells before us which are neither subordinate 

 to, nor co-ordinate with, the rest of the complex 

 of cells. These cells have obviously reached 

 a definite state of independence, nor do thev 

 maintain any direct relations with the different 

 cells of the body. They are, so to say, 

 outside the association of the cells of a particular 

 organ, nor is there any doubt that they produce 

 secretions, the products of their metabolism, which 

 are out of harmony with the blood plasma. And we 

 can well believe that here, too, cells decay, and 

 products pass into the blood which are quite out of 

 harmony with the plasma. 



These ideas afford the possibility of studying, 

 within the body, the action of disharmonious organ- 

 isms of every description, especially of micro- 

 organisms, and their relations towards the rest of the 

 body cells, from a purely physiological point of view. 

 It seems to us well worth while to follow up these 

 conceptions, and to attempt, by means of direct 

 experiments and observations, to bind together in 

 closer relations the two fields of research that are 

 covered by physiology and the study of immunity. 



In the first place, we set ourselves the question : 

 To what measures does an animal organism resort if 

 substances penetrate into its body, and particularly 

 into its blood, which are out of harmony with the 

 species as a whole, or else only with the blood or 



