26 A MANUAL OF BACTERIOLOGY 



room with closed doors ; and the instruments used 

 in the dissection must be previously sterilised in 

 the hot-air steriliser or the Bunsen flame. The 

 animal under examination (e.g. a mouse, rabbit, 

 guinea-pig, etc.) is pinned out on a slab of gutta- 

 percha previously washed in a solution of mercuric 

 chloride (corrosive sublimate). It is now bathed in 

 a stream of the same germicidal agent ; and after 

 having cut away the hair with sterilised scissors, the 

 seat of inoculation, etc., should be examined first, 

 and any pathological characteristics should be noted. 

 If there is any exudation, it should be used for 

 inoculating purposes and microscopical examination. 

 To examine the internal organs, place the animal 

 on its back and make an incision extending (if 

 necessary) from the abdominal to the thoracic 

 region. The organ under examination should be re- 

 moved from the body-cavity, with sterilised scissors 

 and forceps ; and after removal it should be washed 

 with mercuric chloride. The organ is now incised, 

 and the fluid, or a portion of the organ itself (i.e. 

 from the cut) should be used for inoculating various 

 cultivation media. If the blood of the animal is 

 required, it is best obtained from a vein by making 

 an incision with sterilised scissors, and then insert- 

 ing a sterilised capillary pipette or a platinum 

 needle. The blood so obtained should be examined 

 microscopically, and various cultivation media 

 inoculated with it. If the cultivations are con- 

 taminated by the presence of other microbes, frac- 

 tional plate-cultivation must be resorted to, in order 

 to isolate the pathogenic microbe. 



