DILUTION OF THE SPECIFIC SERUM 381 



10. By marking the blood pipette above the level 

 of the serum with the glass cutting knife and snapping 

 the tube at that point, the blood-serum becomes 

 readily accessible for testing purposes. 



If larger quantities of blood are required, the animal, 

 after puncturing the vein, should be inverted, an 

 assistant holding it up by the legs. Blood to the 

 volume of several cubic centimetres will now drop from 

 the punctured vein, and should be caught in a tapering 

 centrifuge tube, the tube transferred to the incubator 

 at 37 C. for two hours, then placed in the centrifugal 

 machine, counterpoised and centrifugalised thoroughly. 

 The three most important of the antibodies referred to 

 which can be demonstrated with a certain amount of 

 facility are agglutinin, opsonin and bacteriolysin ; and 

 the methods of testing for these bodies will now be 

 considered. 



AGGLUTININ. 



Agglutinin is the name given to a substance present 

 in the blood-serum of an animal that has successfully 

 resisted inoculation with a certain micro-organism. 

 This substance possesses the power of collecting 

 together in clumps and masses, or agglutinating watery 

 suspensions of that particular microbe. 



Dilution of the Specific Serum : 



Apparatus required: 



Sterile g A aduated capillary pipettes to contain 10 c. mm. (Fig. 1 7). 



Sterile graduated capillary pipettes to contain 90 c. mm. (Fig. 17). 



Small sterile test-tubes 5X0.5 cm. 



Normal saline solution in flask or test-tube. 



Pipette of specific serum. 



Glass cutting knife, or three-square file. 



Glass capsule, nearly full of dry silver sand, or roll of plasticine. 



Grease pencil. 



