40 INFECTION AND RESISTANCE 



elaborated within the tissues, where resorption is a necessary 

 result. 



Like alkaloids and other organic as well as inorganic drugs, the 

 action of many bacterial poisons is largely selective. Most of these 

 poisons may excite inflammatory reactions if concentrated in any 

 part of the body, but, in addition to this, there is a specific distribu- 

 tion after introduction which indicates that the poison goes into 

 selective relationship with certain tissues and cells. This fact is 

 most clearly illustrated by the bacterial hemotoxins which specifi- 

 cally injure the red blood cells of the infected individual and by 

 such substances as the leukocidin produced by the Staphylococcus 

 aureus, a poison which directly and visibly injures the white blood 

 cells. Here the action is specifically aimed at a well-defined variety 

 of body cell. 



In considering this problem in connection with infectious dis- 

 ease, it is of great importance to distinguish between selective injury 

 by the poisons transported through the body by the lymph, blood, and 

 other channels, on the one hand, and the selective lodgment of the 

 micro-organisms themselves on the other. The latter may occasion- 

 ally depend on local cultural advantages for the particular bacteria 

 in one organ or another, but may just as often be determined by the 

 peculiar manner of entrance to the body which is most suitable for 

 lodgment of the germs in question, and the degree of local resistance 

 at the point of entrance, which determines whether or not the infec- 

 tion shall be locally limited or permitted to invade beyond this 

 point. In the case of a disease like acute anterior poliomyelitis, 

 where our knowledge of the micro-organisms which cause the disease 

 is yet in its infancy, it is impossible to decide whether the injuries 

 noted in the motor areas of the cord and medulla are due to toxins 

 or the lodgment of the germs themselves. In the case of rabies it 

 seems reasonably sure that the micro-organisms themselves select the 

 nervous system. In such instances as the injury of the motor areas 

 by tetanus poison, that of certain peripheral nerves by diphtheria 

 toxin, or even the characteristic lesions of post-syphilitic maladies 

 like tabes, we can be reasonably sure that we are dealing with the 

 specific action of the poisons, independent of actual localized growth 

 of the infectious agents. 



Diphtheria toxin, after distribution through the body, may act 

 upon many different tissues, as is evident by degenerations in the 

 heart muscle, liver, and kidney, and the petechial hemorrhages in 

 serous surfaces. In addition to this general action, however, there is 

 a very marked selection of certain nerve centers. By Meyer and 

 Gottlieb 34 diphtheria toxin is classed as a specific vascular poison. 

 Its action results in a rapid sinking of the blood pressure with final 



34 Meyer and Gottlieb. "Pharmacology Trans. Halsey," Lippincott, 1914, 

 p. 556. 



