462 PROTEIN POISONS 



dissolution occurs more promptly and more completely in 

 the peritoneum of a tuberculous animal. The healthy animal 

 may have to depend upon its phagocytes to combat the 

 invading bacillus, but the tuberculous animal supplies a 

 specific proteolytic enzyme, and to this the fresh invader 

 succumbs. 



Nature is slowly immunizing the white man to tuber- 

 culosis, and the question arises whether or not the process 

 employed by Nature can be aided in any way. There is 

 before the medical profession at this time no greater question 

 than this: Is it possible to aid in eradicating tuberculosis 

 by vaccination? As Romer says, the problem of securing 

 immunity to tuberculosis with a non-infective virus is of 

 great practical importance, and recent work brings the 

 possibility of doing this more and more to the front. What 

 we need is a vaccine. Various methods of modifying the 

 tubercle bacillus so that it could be used as a vaccine have 

 been tried. The bovo vaccine of von Behring w r as tried, 

 but the increased resistance given by it was found to be of 

 short duration. Attempts to reduce its virulence by age, 

 heat, chemicals, and by submitting it to ultraviolet and 

 other rays and emanations have been made. What we 

 need is a tubercle protein sensitizer. It should be soluble, 

 and it should be free from the poisonous group in the protein 

 molecule. In our opinion the nearest approach to this 

 desired substance is the non-poisonous portion of the tubercle 

 protein. So far we have not been able to secure a uniform 

 product. Some preparations seem to fill every requirement. 

 They sensitize animals to the unbroken bacillus, dead or 

 alive, and in surface tuberculous lesions they cause inflam- 

 mation about the tuberculous area, and we have seen 

 the tuberculous tissue slough off and complete recovery 

 result; but other preparations made from the same cellular 

 substance by the same method seem inert. We have had 

 similar difficulties with the sensitizing groups from other 

 proteins. Some preparations from egg-white sensitize to 

 unbroken egg-white, while others seem wholly without 

 effect, and still all are prepared from the same material and 



