INFECTION AND IMMUNITY. 589 



According to the observations of Vaughan, 1 the most 

 important germicidal or protective agents possessed by 

 the body are the nucleins ; and Kossel has shown that 

 the cholera vibrio, streptococcus, staphylococcus, and 

 typhoid bacillus are destroyed by 0.5 per cent, solution 

 of nucleinic acid. 



Hankin believed the globulins or " defensive pro- 

 teids" that he had discovered and the albuminoid 

 bodies studied by Buchner to be identical. The most 

 interesting and, in the light of work that has appeared 

 since, the most important, of Hankin's observations 

 were not those upon the power of these globulins to 

 destroy the vitality of living organisms, but rather 

 those upon the relation between them and the poison- 

 ous metabolic products of growth of the organisms. 

 For example, if the poisonous products of virulent 

 anthrax bacilli be isolated and mixed with the glob- 

 ulin extracted from normal tissues, the experiments of 

 Hankin showed a directly destructive action on the part 

 of the bacterial products. He found that the amount of 

 poisonous albumose produced by the attenuated anthrax 

 bacilli employed as vaccines was much less than that 

 produced by organisms possessing full virulence ; and 

 he suggested that perhaps the protective influence of 

 vaccinations that are practised by introducing into the 

 animal the organisms that have been attentuated in vir- 

 ulence is due to a gradual tolerance acquired by the 

 cells of the tissues to the action of the poison when 

 produced in these small quantities ; in the same way 

 that a tolerance was acquired by the tissues for the 

 venom of the rattlesnake in the experiments of Sewall 2 



1 Vaughan : Medical News, May 20, 1893. 



2 Journal of Physiology, 1887, vol. vii. p. 203. 



