148 THE ACTION OF THE LIVING CELL 



wards the highly spiced condiments which they con- 

 sume daily. 



The development of this tolerance towards the in- 

 troduction of mustard into the stomach naturally 

 raised the question as to whether the animal's increased 

 resistance towards this substance was localized in the 

 gastric mucosa or was a general resistance to be found 

 in all the body tissues. This problem was solved in part 

 by the simple expedient of applying ordinary mustard 

 plasters to the skin of the animal. By this procedure 

 it was observed that coincident with the tolerance to 

 mustard developed by the stomach tissues, the exter- 

 nal application of mustard in the form of a plaster 

 did not result in the usual vesicant efifect. From this 

 we may conclude that the tolerance developed towards 

 the introduction of mustard into the stomach is due to 

 a generalized increase in resistance towards this sub- 

 stance (Turck, 1905). Although the exact nature of 

 this resistance has not been elucidated, it seems clear 

 that no specific antibodies were produced, since all 

 the evidence accumulated by immunologists shows 

 that only proteins are capable of acting as antigens for 

 the production of specific antibodies (Wells, 1925) ; 

 while the irritant principle present in mustard is 

 known to be a volatile oil of non-protein nature. Such 

 being the case, the observed results must be interpreted 

 on other grounds. 



In an earlier chapter, evidence has been presented 

 which indicates that the general toxic effects produced 

 by the introduction of mustard into the stomach may 

 be interpreted as due to the liberation of cytost from 

 the mucosa cells injured by direct contact with the ir- 

 ritant. The tolerance to mustard developed by the 



