82 



Scientific Proceedings (104). 



digitalis in this series was usually low (1.1 gm.). When on 

 occasion we gave larger doses of digitalis, more striking effects on 

 the T-wave were observed. 



48 (1508) 



The isoagglutinins and isohemolysins of the rat. 



By G. L. Rohdenburg (by invitation). 



[From Columbia University, George Crocker Special Research 

 Fund, F. C. Wood, Director.] 



The possibility that some of the irregularities in immunity 

 against transplanted tumors might be correlated with the isoag- 

 glutinins or isohemolysins of the respective hosts prompted an 

 investigation of these substances in the blood of rats. The 

 animals tested were derived from three different sources showing 

 rather marked external as well as biological differences. One 

 group, pure white in color, was resistant to the growth of the 

 Jensen rat sarcoma, showing a very high percentage of natural 

 immunity; a second group, red and white in color, was equally 

 resistant to the growth of the Flexner-Jobling rat carcinoma; a 

 third group, hooded black and white, was equally susceptible to 

 both tumor strains. 



Fifty animals were tested in the following manner for the 

 presence of either isoagglutinins or isohemolysins. Nine drops of 

 serum were mixed with one drop of a 5 per cent, suspension of 

 washed red cells in a test tube. In the first series of ten animals 

 the serum of each animal was tested against the cells of every 

 other animal, and the cells of each animal were tested against 

 the serum of every other. Five series were carried through in 

 this fashion, each series consisting of three animals of two of the 

 groups and four of a third group. 



Tests between animals of the same strain or between animals 

 of different strains showed that neither agglutinins or hemolysins 

 were demonstrable, this being contrary to the well-established 

 phenomena in man, where four distinct groups have been found. 



