46 AIDS TO BACTERIOLOGY 



incisions, and a third set for removing the organs. The 

 material from which cultures are to be made depends on 

 the organism suspected. The site of inoculation, the 

 spleen, or the blood, may furnish the organism in most 

 abundance. Before any organ is opened it is first seared 

 with the cautery. Blood and peritoneal fluid may be 

 collected in sterile capillary pipettes. Blood is taken from 

 the right ventricle. After dissection the animal is 

 drenched with disinfectant, and, together with the board, 

 is burnt at once. The greatest care must be taken to 

 prevent the dissemination of infectious matter, and in 

 the event of any material being dropped, it must be 

 immediately swabbed up with disinfectant. 



Blood Preparations. Small quantities of blood are 

 obtained by pricking a finger or lobe of the ear with a 

 bayonet-pointed needle after sterilisation of the skin 

 by rubbing with alcohol and ether. For a Widal reaction 

 the blood is taken up in a capillary pipette. For other 

 &erum tests Wright's capsules are used. For blood-films, 

 the exuded drop of blood is touched with the edge of a 

 microscopical slide, and then brought in contact with an- 

 other slide, near its end. When the drop has spread across 

 the slide, the first is gradually drawn or pushed across the 

 horizontal one. The thickness of the film can be varied 

 at will by altering the angle at which the top slide is drawn 

 across the other. For determining the nature of organisms 

 in septicaemia, larger quantities of blood are required 

 up to 5 or 10 c.c. Such blood is taken, with aseptic pre- 

 cautions, from a superficial vein (the median basilic or 

 median cephalic veins are convenient) with a sterile glass 

 syringe, a tourniquet being applied to produce venous 

 congestion. The blood is introduced in quantities of \ c.c. 

 into agar plates or broth-tubes. 



CHAPTER IV 



THE MICROSCOPIC EXAMINATION OF 

 BACTERIA 



LIVING bacteria are observed in ' hanging drops,' and 

 dead bacteria in film preparations or in sections of tissue. 

 For bacteriological purposes, cover-glasses | inch in 



