178 VETERINARY BACTERIOLOGY 



has been transferred in the serum. An animal sensitized by the 

 injection of a foreign protein or sensibilisinogen is said to show 

 active anaphylaxis, one which is sensitized by the serum or allergin 

 of another sensitized animal is said to show passive anaphylaxis. 

 This allergin is specific, that is, an animal sensitized to egg-white 

 will not show anaphy lactic reaction when injected with horse 

 serum. This fact might be utilized in testing for proteins of 

 different kinds, were it not for the much simpler technic of the 

 precipitation reaction. It is made use of, as will be noted later, in 

 certain disease diagnoses. How this allergin is formed is uncer- 

 tain. Probably the primary injection of the protein stimulates 

 the cells of the body to increase their normal power of assimilation. 

 This is accomplished by certain receptors, which break up the 

 protein (proteolysis) , or so change it that it can be rapidly utilized 

 by the cell. These receptors increase in numbers, and are thrown 

 off into the serum, where they are as capable of transforming the 

 protein when injected as when still attached to the protoplasm. 

 The allergin retains its activity after heating to temperatures of 

 56 to 58; it is, therefore, regarded by Anderson and Frost as 

 thermostabile. These authors believe that " anaphy lactic shock 

 is due to disturbance of metabolic activities of vital cells rather 

 than to the specific (permanent) intoxication of the cells." In 

 other words, there is no proof that the substances produced from 

 the homologous protein (sensibilisinogen) are poisonous; the shock 

 of anaphylaxis comes from the disturbance of metabolism of the 

 body-cells due to the sudden flood of readily assimilable materials. 

 Antianaphylaxis. An animal which has just recovered from 

 an anaphylactic shock does not show the same symptoms when a 

 second injection is made soon after. Again, if a small injection 

 be made into a sensitized pig, a large dose a few hours later will 

 fail to show the reaction. The possible explanation for this 

 phenomenon has been offered, to the effect that the allergin is in 

 each case all used up by the first injections, and the second injec- 

 tion, therefore, is transformed too slowly to allow any reaction 

 to become apparent. Such an animal is said to be in a state of 

 antianaphylaxis. 



Immunity. Continued injections of the antigen (sensibilisin- 

 ogen) result usually in the development of an immunity in the 



