THE PHENOMENA OF INFECTION 87 



proteins of the fluids of the animal's body arc 

 quickly built into the bacterial cell and growth 

 and multiplication result. Body proteins are 

 converted into bacterial proteins. This process 

 proceeds so smoothly that as a rule during the 

 time when its development is most rapid the 

 host is quite unaware of the presence of his un- 

 desired guest. Whole molecules of albumins 

 and globulins are taken into the bacteria t and 

 built into the more complicated bacterial cell. 

 This is the period of incubation in an infection. 

 The body cells are not prepared to combat the 

 invader during this period. Finally the body 

 cells react and begin the elaboration of fer- 

 ments which destroy the bacterial proteins. 

 This is quite a different process. Complex, 

 cellular proteins are split into simpler ones and 

 protein poisons are set free. 



During the period of incubation of an infec- 

 tious disease, the infecting organism supplies 

 the ferment, the simple, soluble proteins of the 

 body fluids constitute the substrate, the process 

 is essentially constructive, no poison is set free 

 and there are no recognizable clinical symp- 

 toms. During the active progress of an infec- 

 tious disease, the body cells supply the ferment, 

 the complex, bacterial, cellular proteins consti- 

 tute the substrate, the process is essentially de- 



