INFECTION AND IMMUNITY. 537 



that we have here a condition with which mechanical 

 plugging of the capillaries could have had no connec- 

 tion, for thei'e are no organisms in the blood to interfere 

 with its circulation. Oar hypothesis then with regard 

 to the condition found in our first case of anthrax is 

 again not tenable. Similarly, if an animal that has 

 died of tetanus be examined, we do not find the bacilli 

 in the tissues and circulating fluids generally, and, in- 

 deed, often fail to find them even at the point of injury. 

 Plainly, the fatal results following upon inoculations 

 with the diphtheria and the tetanus bacillus, with their 

 accompanying tissue-changes, occur from the presence 

 of a something that cannot be detected by either cult- 

 ural or microscopic methods, and this something can be 

 only a soluble substance that is produced by the growing 

 bacteria at the site of inoculation, gains access to the 

 circulation, and through this channel causes death, for 

 it is scarcely to be imagined that the insignificant wound 

 made in the course of inoculation could per se have had 

 this effect. In other words, these latter animals have 

 died from what is called toxcemia (poison in the blood), 

 a condition distinctly different from septiccemia, as seen 

 in our first animal dead of anthrax. 



There are, again, other infectious diseases, many of 

 which are known to present variations from what might 

 be considered a typical course, that may still further 

 serve to support the view that infection is a process in 

 which the mechanical effect of organisms in the circu- 

 lating fluids is of little consequence. Conspicuous 

 among these are the infections that follow upon the 

 introduction into the tissues of susceptible animals of 

 cultures of microcooeus lanceolatus (pneumococcus), of 

 the bacillus of chicken cholera, and of the organisms con- 



