168 THE ACTION OF THE LIVING CELL 



page 1 14, we may suppose that their natural resistance 

 to cytost has been increased beyond that of similar un- 

 treated animals which have been kept under other- 

 wise identical conditions. As will be shown pres- 

 ently, this supposition is justified by the experimental 

 results. Such being the case, we may reasonably speak 

 of such animals as having been actively immunized 

 to cytost by the treatment they have undergone. It 

 must be stressed, however, that the term immunity is 

 here used in a relative manner, for we cannot by any 

 treatment render an animal absolutely immune to cy- 

 tost. All we can do is to raise his degree of tolerance 

 to cytost above that of his untreated mates. 



If a series of cytost injections, which leads to in- 

 creased weight and general health, really is capable 

 of raising an animal's resistance to cytost, then ani- 

 mals so treated should be more resistant to shock than 

 are animals whose resistance has not been so raised. 

 This point is easily settled by experiment. A potent 

 cytost preparation prepared as previously described 

 from autolyzed cat's muscle was first assayed by injec- 

 tion into normal cats in order to find the dosage neces- 

 sary to cause a severe shock. This dosage was then 

 injected under parallel conditions into normal cats 

 and into cats actively immunized to cytost, as above 

 described. The untreated animals always passed into 

 severe shock frequently resulting in death, whereas the 

 actively immunized animals developed a shock of con- 

 siderably lesser degree and but few fatalities resulted. 



When the quantity of cytost injected was reduced 

 to such an amount that it caused a severe but non-fatal 

 shock in normal animals, the actively immunized ani- 

 mals were found upon injection to suffer shock in but 



