THE SENSITIZERS OF SERA. 247 



With these materials the following tubes were prepared : 



Tube 1 Cow milk 0.2 c.c. 



S. rabbit > milk, 56 degrees 0.6 c.c. 



Rabbit alexin 0.1 c.c. 



Tube 2 Cow milk 0.2 c.c. 



S. normal rabbit, 56 degrees 0.6 c.c. 



Rabbit alexin 0.1 c.c. 



Tube 3 Salt solution of 0.75 per cent 0.2 c.c. 



S. rabbit > milk, 56 degrees 0.6 c.c. 



Rabbit alexin 0.1 c.c. 



Tube 4 Salt solution 0.2 c.c. 



S. normal rabbit, 56 degrees 0.6 c.c. 



Rabbit alexin 0.1 c.c. 



Tube 5 Cow milk 0.2 c.c. 



S. rabbit > milk, 56 degrees 0.6 c.c. 



Salt solution 0.1 c.c. 



Tube 6 Cow milk 0.2 c.c. 



S. normal rabbit, 56 degrees 0.6 c.c. 



Salt solution 0.1 c.c. 



Tubes 1 and 2. In these tubes the action of the rabbit > milk serum on cow 

 milk is compared with that of normal rabbit serum. 



Tubes 3 and 4. Show the effect of the sera alone on the alexin. 



Tubes 5 and 6. Contain no alexin and show that heated serum will not pro- 

 duce hemolysis without alexin, and act as controls to those tubes in which the 

 alexin is not affected. 



These tubes are left 5 hours at room temperature, with agitation 

 from time to time. To each tube is then added one-thirtieth of a 

 cubic centimeter of sensitized hen corpuscles.* Following is the 

 resultant hemolysis after 2 hours at room temperature, which result 

 is found to remain constant the next day: 



In tubes 2, 3 and 4 hemolysis is complete and uniformly rapid; 

 it is evident in 30 minutes and has become complete in 1 hour and 

 30 minutes. Tubes 1, 5 and 6 show no hemolysis even on the fol- 

 lowing day. What conclusion is to be drawn? In tubes 5 and 6 

 there is no hemolysis because no alexin is present; in tubes 3 and 4 

 the alexin has remained free when mixed with the heated rabbit 

 > milk serum or with heated normal rabbit serum; and in tube 2 the 

 milk plus normal serum has caused no fixation. Tube 1 has acted 

 as tubes 5 and 6 that had no alexin. The alexin added could not 

 have been fixed by the heated rabbit > milk serum (tube 3) nor by 



* Defibrinated hen blood is washed in an excess of normal saline, centrifugal- 

 ized, the supernatant fluid pipetted off, and the original level of the blood re- 

 established. This washed blood is mixed with two volumes of heated (56 degrees) 

 serum from a rabbit that has received several injections of hen blood. 



