106 APPLIED IMMUNOLOGY 



up to its original volume with normal salt solution, 

 making a 5 per cent, suspension. Practically, a larger 

 amount of suspension can be prepared in the same 

 number of centrifuge tubes, by originally placing say 

 3 c.c. of whole blood in each, washing and centrifug- 

 ing three or four times, and after the final washing 

 bringing the volume up to 30 c.c. For injection into 

 the rabbit, a 10 per cent, suspension of the corpuscles 

 is more suitable than a 5 per cent, suspension, so after 

 the final washing the fluid in a tube containing origi- 

 nally 1 c.c. of whole blood or 0.5 c.c. of corpuscles is 

 brought up to a total volume of only 5 c.c. 



Immunization of the Rabbit to Sheep's Corpuscles, 

 — The suspension of sheep's corpuscles prepared as 

 described i^ove may be injected into the rabbit either 

 intraperitoneally or intravenously. Since much larger 

 amounts of suspension and a longer time for immu- 

 nization are required by the former method, we have 

 discarded it entirely in favor of the intravenous 

 method. The latter is just as simple, and if 

 proper precautions against infection and injection 

 of air be taken, is quite safe. For the first injection 

 about 1 c.c. of the 10 per cent, corpuscle suspension is 

 drawn up into an all-glass hypodermic syringe of 2 

 c.c. capacity and fitted with the usual fine needle; the 

 smaller the needle the better. The marginal vein of 

 the rabbit's ear is made prominent by wiping it with 



