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A MANUAL OF BACTERIOLOGY 



of caustic potash). By this method the virulent 

 power gradually diminishes, and finally disappears. 

 By using attenuated viruses of varying intensities 

 (prepared by desiccation), Pasteur has successfully 

 treated numberless animals and human beings which 

 are now refractory to rabies. 



To prepare the inoculating fluid a mad dog is 

 killed, and the brain and medulla oblongata are 

 carefully removed with sterilised instruments, etc. 

 Very small pieces of the medulla oblongata and of 



, the Central canal are then 



placed in a sterilised glass. 

 They are triturated with a glass 

 rod, and when reduced to a fine 

 jelly-like mass sterilised veal 

 bouillon is added in quantity 

 to about half a table-spoonful. 

 This dilute dog- virus is used 

 for inoculating a rabbit on the 

 surface of the brain. A full- 

 grown living rabbit is placed 

 upon a dissecting board, flat 

 on its abdomen, and its four limbs secured 

 by strings to pegs driven in the wood (Fig. 41). 

 After this the animal is placed under the influence 

 of chloroform. The hair is cut away, and an inci- 

 sion, one inch long, is made from a point midway 

 between the eyes. The operator cuts down to the 

 skull, which is then trepanned (Fig. 4 la), and a little 

 circular disc of bone is removed, as far as possible 

 without injuring the external membrane of the 

 brain. At this point the operator takes a hypoder- 



FIG. 41. TREPANNING 

 A RABBIT. 



