Ii8 IMMUNE SERA 



Sera which are badly contaminated or which are 

 haemolyzed should not be tested. 



Sheep Cells. The neck of a sheep is shaved in 

 the area surrounding the jugular vein. The skin 

 washed and rubbed with alcohol, a hollow needle 

 inserted and the required amount of blood allowed 

 to flow into a sterile bottle which contains a few 

 glass beads. The bottle is shaken until the blood 

 has clotted and the cells remain suspended in the 

 serum. A quantity of this serum is placed in a 

 centrifuge tube and an excess normal saline added. 

 The cells are then centrifuged, the supernatant fluid 

 removed and the cells again suspended by an addi- 

 tion of normal saline. This is repeated until the 

 cells have been washed five times. The packed cells 

 are then made up in a 5 per cent suspension and 

 are ready for use. If, in the last washing, the 

 centrifuge is allowed to run for a definite number 

 of minutes the suspension will be uniform from day 

 to day. 



Amboceptor. There are various ways in which 

 a potent amboceptor may be produced. The suc- 

 cess of the method, within certain limits, depends 

 more upon the individual rabbit than upon the 

 amount of sheep cells injected. Three injections of 

 of i cc. of 50 per cent sheep cell suspension on 

 alternate days given intravenously have proven 

 satisfactory in this laboratory. The rabbit is bled 

 under anaesthesia on the tenth day after the last 



