272 SUSCEPTIBILITY AND IMMUNITY. 



thrown down with ammonium sulphate. The finely pulverized pre- 

 cipitate is shaken up with pure chloroform, and when this is allowed 

 to stand the antitoxin rises to the surface while the ammonium salt 

 sinks to the bottom. By filling the vessel to the margin with chloro- 

 form, the antitoxin floating on the surface can be skimmed off, after 

 which it quickly dries. By this method the considerable loss which 

 occurred in the dialyzer, used in the previously described method, is 

 avoided. 



A most interesting question presents itself in connection with the 

 discovery of the antitoxins. Does the animal which is immune 

 from the toxic action of any particular toxalbumin also have an im- 

 munity for other toxic proteids of the same class? The experimental 

 evidence on record indicates that it does not. In Ehrlich's experi- 

 ments with ricin and abrin he ascertained that an animal which had 

 been made immune against one of these subtances was quite as sus- 

 ceptible to the toxic action of the other as if it did not possess this 

 immunity, i.e., the antitoxin of ricin does not destroy abrin, and 

 vice versa. As an illustration of the fact, he states that in one ex- 

 periment a rabbit was made immune for ricin to such an extent that 

 the introduction into its eye of this substance in powder produced no 

 inflammatory reaction ; but the subsequent introduction of a solution 

 of abrin, of 1 to 10,000, caused a violent inflammation. 



Evidently these facts are of the same order as those relating to 

 immunity from infectious diseases, and, taken in connection with the 

 experimental data previously referred to, give strong support to the 

 view that the morbid phenomena in all diseases of this class are due 

 to the specific toxic action of substances resembling the toxalbumins 

 already discovered ; and that acquired immunity from any one of 

 these diseases results from the formation of an antitoxin in the body 

 of the immune animal. 



Hankin calls these substances produced in the bodies of immune 

 animals " defensive proteids," and proposes to classify them as fol- 

 lows : First, those occurring naturally in normal animals, which he 

 calls sozins ; second, those occurring in animals that have acquired 

 an artificial immunity these he calls phylaxins. Each of these 

 classes of defensive proteids is further subdivided into those which 

 act upon the pathogenic microorganism itself and those which act 

 upon its toxic products. These subclasses are distinguished by the 

 prefixes myco and t oxo attached to the class name. 



In accordance with this classification a mycosozin is a defensive 

 proteid, found in the body of a normal animal, which has the power 

 of destroying bacteria. 



A toxosozin is a defensive proteid, found in the body of a normal 



