642 THE INTERNAL SECRETIONS AND IMMUNITY. 



What is the nature of these antitoxic bodies? Or, in other 

 words, what is "antitoxin"? 



The source of "antitoxin" has not been traced to any par- 

 ticular organ or" set of organs. All that is positively known is 

 that in immunized animals i.e., animals into which toxins 

 have been injected in gradually increased doses it appears in 

 the blood in constantly increasing quantities. In other words, 

 its relative quantity is constantly changing, and it fluctuates 

 with the quantity of toxins introduced into the circulation of 

 a given animal. 



That the toxins injected into animals to obtain anti- 

 toxic serum for purposes of immunization act on the adrenal 

 system precisely as do other poisons needs hardly to be em- 

 phasized. When diphtheria toxins are injected, for instance, a 

 feature of the earlier period of the treatment is the tendency 

 to paralysis, which is often followed by rapid death. This 

 association between paralysis and sudden death is very sug- 

 gestive when we recall the influence of powerful toxics on the 

 adrenals, and the induction of paralysis as an advanced symp- 

 tom of 'the stage of insufficiency. Again, each injection causes 

 a marked reaction, attended with a rise of temperature which 

 sometimes reaches several degrees. As the doses of toxin are 

 very gradually increased, it takes months to bring the animal's 

 serum to the immunizing standard: i.e., to that state when it 

 contains, in a given quantity, a sufficient amount of antitoxin 

 to confer immunity when that given quantity is injected into 

 unprotected animals or human beings. 



At the end of these months, however, an important change 

 in the resistance of the animal to the poisonous effects of the 

 toxins occurs: it is able to stand several hundred times the 

 dose of toxin that would have proven fatal at the start. 

 Ehrlich's experiments with abrin, the toxalbumin of the jequir- 

 ity-bean, and ricin, that of the castor-bean, have shown that im- 

 munity to their poisonous effects could be conferred precisely 

 in the same way. These purely vegetable poisons, in other 

 words, not only behave as do toxins, but treatment of animals 

 in the manner depicted above produces similar results, even 

 to the extent of conferring immunity. Snake-venom again 

 affirms its kinship to toxins and vegetable toxalbumins by 



