HEMOLYTIC SERA AND THEIR ANTITOXINS. 193 



pended stromata.* To equal amounts of these two fluids equal 

 amounts of sensitizing substance and of alexin (from a normal 

 guinea-pig) are added. The alexin should not be in too large 

 amount. The mixtures are then shaken and, after a certain time, 

 well-sensitized rabbit corpuscles are added to each fluid. It is 

 found that these corpuscles are not hemolyzed or are only slightly 

 hemolyzed in the fluid containing the stromata, but, on the contrary, 

 are rapidly dissolved in the limpid red fluid. From this experi- 

 ment it may be concluded that the property possessed by the red blood 

 corpuscles of absorbing alexin in presence of the sensitizing substance 

 is due to their stromata. 



For another experiment a suitable dose of sensitizing substance 

 (that is, hemolytic serum heated to 55 degrees) may be added to the 

 two fluids. After shaking and allowing to stand for a time the 

 second mixture is centrifugalized to separate out the stromata, and 

 the supernatant fluid is decanted. It is then demonstrable that 

 this fluid contains no sensitizing substance, since the subsequent 

 addition of red blood cells and normal guinea-pig serum gives no 

 hemotysis. The property of absorbing the sensitizing substance also 

 belongs, then, to the stromata. 



In yet another experiment it may be shown that the stromata 

 absorb alexin when the sensitizing substance is present, whereas 

 they do not fix it if the latter substance is absent. For this experi- 

 ment a thick emulsion of stromata is prepared to which a large 

 amount of salt solution is added. The mixture is centrifugalized 

 and the limpid pinkish supernatant fluid decanted. The washing 

 with salt solution is repeated until the emulsion of stromata is quite 

 white and free from hemoglobin. The emulsion is then divided 

 into two equal parts, to each of which the same dose of alexin (serum 

 of a normal guinea-pig) is added. To the first mixture a small 

 amount of sensitizer is then added and to the second the same 

 amount of normal guinea-pig serum also heated to 55 degrees. It 

 may be demonstrated in the usual manner that in the first mixture 

 the alexin has disappeared from the fluid by fixation on the 

 stromata; there is no absorption of the alexin in the second fluid 

 containing no sensitizing substance. 



* It is well to determine, of course, that there are no intact corpuscles remaining 

 among these stromata. 



