64 THE GERM THEORY OF DISEASE. 



they produced a different disease entirely, which was not seen 

 in the experiments on the house mouse, for the reason that it 

 was killed by the first and more quickly acting organism, be- 

 fore the second had time to produce its effects. This new 

 disease ran a course identical with the dreaded hospital gan- 

 grene. The organism did not pass into the circulation at all. 

 It spread by its growth merely, and destroyed all tissues with 

 which it came in contact, until vital organs were reached and 

 the animal destroyed. The parasite was found only in the 

 diseased tissue, never in the blood. 



Dr. Koch says of this : " These appearances lead us to the 

 conclusion that the action of these micrococci in causing the 

 gangrene is somewhat as follows : Introduced by inoculation 

 into living animal tissues, they multiply, and as a part of 

 their vegetative process, they excrete soluble substances which 

 get into the surrounding tissues by diffusion. When greatly 

 concentrated, as in the neighborhood of the micrococci, this 

 product. of the organisms has such a deleterious effect on the 

 cells that these perish and finally completely disappear. At 

 a greater distance from the micrococci the poison becomes 

 more diluted and acts less intensely, only producing inflam- 

 mation and accumulation of lymph corpuscles. Thus it 

 happens that the micrococci are always found in the gan- 

 grenous tissue, and that, in extending, they are preceded by a 

 wall of nuclei, which constantly melts down on the side 

 directed towards them, while, on the opposite side it is as con- 

 stantly renewed by lymph corpuscles deposited afresh." 



Inoculation with the juices of the dead tissue never failed 

 to induce the disease. Inoculation with the blood did not 

 induce the disease in any case. When the house mouse was 

 inoculated with this material, the disease induced was pre- 

 cisely the same as in the field mouse. Thus, these two forms 

 of organism, one a very minute bacillus, the bacillus septicus, 



