Pleuro- Pneumonia of Cattle. 207 



Experiments were accordingly made in order to remove all 

 traces of conglutinin from various bovine sera, which were after- 

 wards tested to determine the effect the experiment had produced 

 on their complement fixing properties. 



Bordet and Gay (3) have shown that conglutinin is not des- 

 troyed by heating bovine serum at a temperature of 56°C. To 

 attempt to destroy conglutinin by heating at higher temperatures 

 would probably render the serum useless for test purposes after- 

 wards, consequently some other method had to be adopted in 

 order to get rid of it. If inactivated bovine serum plus com- 

 plement is added to a saline suspension of red blood cells previ- 

 ously sensitised by their specific sensitiser, conglutination of the 

 red blood cells takes place more or less immediately on mixing, 

 and in the reaction produced the conglutinin becomes used up. 

 This conglutination is followed after a varying time by haemo- 

 lysis of the red blood cells, the time depending on the source 

 and activity of the complement used in the experiment. If, then, 

 when conglutination occurs in such an experiment, and before 

 haemolysis has time to occur, the mixture is rapidly centrifuged, 

 the supernatent fluid can be pipetted off from the deposit of red 

 olood cells, and will be found to contain little or no conglutinin ; 

 the absence of conglutinin depending on the degree of saturation 

 -of the bovine serum by the red blood cells. Thus it is possible 

 to deprive a bovine serum of its conglutinin. 



Certain bovine sera, which had been taken from animals known 

 to be affected with active lesions of contagious pleuro-pneu- 

 monia, were used for experimental purposes. The experiments 

 carrid out were as follows : — 



Experiment i. — To 10 c.c.s. of a 5 per cent, suspension in saline 

 of washed red blood cells of a sheep, which have been previously 

 sensitised by their specific amboceptor, 1 c.c. of fresh horse serum 

 is added. Mix, and allow to stand at room temperature for one 

 hour. Haemolysis does not occur in one hour, because the horse 

 serum — although it contains complement — contains only a very 

 weak complement. Centrifuge the mixture, and carefully remove 

 the fluid from the deposit of cells. The cells are then washed in 

 saline solution, which is afterwards removed. Add then to the 

 deposit of cells, 1 c.c. of saline solution, and 1 c.c. inactivated 

 bovine serum (No. 51 positive). Conglutination of the red blood 

 cells takes place almost immediately on mixing. Carefully re- 

 move the supernatent fluid, and dilute it 1 part in 4 of saline 

 solution, thus forming a 1 in 10 dilution of the original amount 



