IO 



Scientific Proceedings (25). 



the hypersensitive condition. Nine days later the animals were 

 all treated as follows : 



None of the animals showed any marked symptoms under this 

 treatment. 



September 21, 10 a. m., one of the three received 1.5 cc 

 normal serum intracardiac. No symptoms. 



The other two animals were bled and 1 5 cc. of the mixed 

 defibrinated blood were at once injected into the peritoneal cavity 

 of a fresh normal guinea pig weighing 240 grams. After an 

 interval of thirty hours, this pig received 1.75 cc. normal horse 

 serum intracardiac. No symptoms. 



Thus a complete immunity to the reaction can be developed in 

 about twenty four hours and at the same time the blood loses its 

 power to transmit the reaction, presumably because the antibody 

 has been exhausted. The animal is probably in the condition of 

 a normal animal which has had a single large dose of horse serum. 

 Preliminary experiments make it seem possible, however, that the 

 return to the hypersensitive state may be accomplished in less than 

 the normal incubation period. This would be in analogy with the 

 acceleration of reaction noted in cases of serum disease in human 

 beings. 



If normal guinea pigs are treated repeatedly with very small 



doses of horse serum (2 0V0" c - c - - TFiJo" c,c -) or w ' tn re P eate d non- 

 fatal toxin-antitoxin mixtures, or if hypersensitive animals are fed 

 with horse serum, they may subsequently be found hypersensitive 

 in the usual way. In a percentage of cases, however, they will 

 react differently when treated with 5 cc of horse serum subcu- 

 taneously. Acute symptoms are slight or absent. But at twenty 

 four hours the animal may be very sick and have a large subcu- 

 taneous edema. The edema may progress and death occur on the 

 second or third day, or in less severe cases the animal may survive 

 with extensive cutaneous and subcutaneous necrosis. Post mortem 

 examination on the third and fourth day shows interesting features. 



Sept. 19 

 Sept. 20 

 Sept. 20 

 Sept. 20 



8 p. m., o. 5 cc normal horse serum subcutaneously. 



8 a.m., 2.0 " " " " " 



12 m., 5.0 " " " " " 



8 p.m., 5.0 " *' " " intraperitoneally. 



