126 A MANUAL OF BACTERIOLOGY 



in antitoxin work, it is generally possible to bleed from a 

 superficial vein. The needle of a syringe may be passed 

 into the heart of a guinea-pig and 2-3 c.c. of blood with- 

 drawn without injury to the animal. In the rabbit blood 

 may be obtained by passing the fine point of a piece of 

 glass tubing, drawn out and bent to a convenient angle, 

 or the needle of a syringe, into one of the ear veins 

 and aspirating the blood into it. Or the vein may 

 be punctured and the blood allowed to drip into a small 

 tube. 



Blood may be obtained from a patient for the aggluti- 

 nation reaction, for microscopical examination, or for 

 culture experiments, by pricking the finger or the lobe of 

 the ear with a sterile needle, preferably a flat one of the 

 " Hagedorn " type, or with half a steel pen (nib) or a 

 glass point ; for disinfection, the skin may be rubbed with 

 a little alcohol or ether. After swinging the arm and 

 winding a piece of rubber tubing round the finger or 

 thumb and pricking 1-3 c.c. may generally be obtained. 

 The blood may be collected in a small test-tube, vaccine 

 tubes, small bulbous tubes (Fig. 7, p. 52), or Wright's 

 tubes (Fig. 35, p. 215). 



If the tube with contained blood is sealed in the flame, 

 and is afterwards centrifuged to obtain clear serum, care 

 should be taken that one end is not wetted with the blood, 

 and this dry end should be sealed first so as to obtain a 

 perfect seal, When centrifuging, this sealed end should 

 be placed downwards in the centrifuge " bucket." 



Organisms, in natural infections in man, are usually 

 present only in small numbers in the blood, and for 

 demonstrating them by culture methods it is necessary 

 to withdraw 2-5 c.c. from a superficial or deep vein by 

 means of a sterile syringe under aseptic conditions, and to 

 inseminate broth tubes or agar plates each with 0'5 c.c. of 

 the blood. 



