208 G. G. Heslop: 



of bovine serum used. The complement fixing properties of this; 

 diluted serum are then tested. As a control, a 1 in 10 dilution 

 of serum (No. 51) from the same bulk sample, but which has- 

 not been treated for extraction of conglutinin, is also tested. 



The untreated serum gives a strongly positive reaction, when- 

 tested, whereas the treated serum gives a negative reaction. The 

 treated serum is found to be devoid of conglutinin, but in the 

 process of extracting the conglutinin, the specific complement 

 fixing antibodies have also disappeared. It is thus apparent that 

 serum so treated is rendered useless for the purpose of a com- 

 plement fixation test for contagious pleuro-pneumonia. 



Experiment 2. — To 3.5 c.c.s. of a 10 per cent, suspension o£ 

 the washed red blood cells of a guinea-pig there is added 1 c.c.. 

 saline solution, and 0.5 c.c. of fresh horse serum. (Horse serum 

 contains a natural sensitiser for guinea-pig's cells, the fresh horse 

 serum also contains complement). Mix thoroughly by shaking, 

 and allow to stand at room temperature for one hour, then cen- 

 trifuge. Pipette off the fluid, and add 2 c.c.s. saline solution to- 

 the deposit of cells. Mix and centrifuge. Pipette off the saline 

 solution, and add to the deposit of cells, 2 c.c.s. saline solution,, 

 and 0.5 c.c. inactivated bovine serum (Serum No. 94, positive). 

 Mix, and allow to stand at room temperature for 30 minutes, then 

 centrifuge. Carefully remove the fluid from the deposit oi cells, 

 and add to this fluid 2.5 c.c.s. of saline solution, thus forming, 

 a 1 in 10 dilution of the original amount of bovine serum used. 

 This dilution of treated bovine serum is then tested for its com- 

 plement fixing properties. It gives a feebly positive reaction, 

 whereas untreated serum No. 94, from the same bulk sample,, 

 gives a strongly positive reaction. It is found, on testing, that 

 the experiment to remove the conglutinin from the serum so< 

 treated, has failed to remove it completely, although the greater 

 bulk of it has been extracted. 



Experiment j. — To 10 c.c.s. of a 10 per cent, suspension in 

 saline solution of the washed red blood cells of a goat there is 

 added 1 c.c. of fresh unheated bovine serum (Serum No. 94, posi- 

 tive). (Bovine serum contains a natural sensitiser for goat's cells, 

 and fresh bovine serum also contains complement). Allow the 

 mixture of serum and cells to stand at room temperature for 20' 

 minutes. Conglutination of the red blood cells takes place a few 

 minutes after the mixture is made. Centrifuge and carefully 

 pipette off the supernatent fluid from the deposit of red blood 

 cells. The supernatent fluid is bovine serum diluted 1 in ID 





