268 APPLIED BACTERIOLOGY 



between half and three-quarters of an inch behind a line 

 drawn between the middle of the two eyes he carefully 

 applies it to the median line and cuts through the bone. 

 The circular piece being lifted up and removed by means 

 of a strong curved needle, the cerebral membranes are now 

 exposed. He then takes a special kind of hypodermic, 

 syringe, fills it from the glass which contains the emulsion 

 of the dog's brain, and injects about 1 c.c. under the 

 dura mater. The wound is then freely bathed with the 

 5 per cent, aqueous solution of carbolic acid, and two or 

 three stitches are put in, to bring the skin together again, 

 the wound is once more dressed with the carbolized solution, 

 and the operation is finished. In skilled hands the process 

 is a very simple one — few fatal results occur, the wound 

 soon heals, and the animal will generally eat directly it 

 recovers from the effect of the anaesthetic. It is usual to 

 inoculate two rabbits at the same time, to avoid accidents, 

 and thus prevent a break in the series of passages from 

 one animal to another. After inoculation the rabbits are 

 placed two together in strong cages, each of which bears 

 a label stating the date, weight of animals, their colour, 

 nature of inoculation, etc. 



Babies in the rabbit assumes the paralytic or dumb form. 

 The hind-legs first become paralyzed, and gradually the 

 paralysis ascends until the whole body is involved ; the 

 animal then lies quite helpless, and dies shortly after. 

 Another rabbit is now inoculated from the medulla of the 

 dead one, by the same method as described above, and re- 

 peated passages are made from rabbit to rabbit until the 

 incubation period is reduced to seven days. This period 

 will probably become constant after a passage of the virus 

 through about forty or fifty rabbits, though at the first few 

 passages it will be found to be much longer — from fourteen 

 to twenty days in many cases. About 1 cm. of the spinal 



