142 LABORATORY BAC1''ERI0L0GY 



inoculation of rabbits lias been most reliable. The injection through 

 the optic foramen has been tried. The subdural method is, briefly 

 stated, as follows : 



The brain of the suspected animal is removed with aseptic pre- 

 cautions as soon as possible after death. A small piece of the brain 

 or spinal cord is placed in a sterile mortar and thoroughly ground 

 with a few cubic centimetres of sterilized water or bouillon. This 

 forms the suspension to be injected. The hands of the operator and 

 all instruments are carefully disinfected. The rabbit is etherized, 

 the hair clipped from the head between the eyes and ears, and the skin 

 thoroughly washed and disinfected. A longitudinal incision is then 

 made, the skin and subcutaneous tissue held back by means of a 

 tenaculum, a crucial incision is made in the periosteum on one side of 

 the median line to avoid hemorrhage from the longitudinal sinus, 

 and the four corners of the periosteum reflected or pushed back. 

 By the aid of a trephine a small button of bone is easily removed, 

 leaving the dura mater exposed. With a hypodermic syringe a 

 drop or more of the rabid brain suspension is injected beneath the 

 dura, the periosteum is replaced, the skin careftilly sutured and dis- 

 infected, and the rabbit returned to its cage. As soon as the influ- 

 ence of the anaesthetic has passed off, the rabbit shows no appearance 

 of discomfort. If the operation is performed in the forenoon, the 

 animal partakes of its evening meal with the usual relish. The 

 inoculation wound heals rapidly and the rabbit exhibits every ap- 

 pearance of being in perfect health until the beginning of the specific 

 symptoms, which occur ordinarily in from 15 to 30 days, usually 

 in about 20 days after the inoculation. Occasionally the symptoms 

 appear earlier than 15 days and in some cases the rabbits are not 

 attacked for from i to 3 months. 



The symptoms following the inoculations have in my experience 

 been quite uniform, the only pronounced difference being in the 

 length of time the rabbits hved after the initial manifestation of 

 the disease. The fact should be clearly stated that rabbits do 

 not ordinarily become furious. In some instances they are some- 

 what nervous for a day or two preceding the paralysis. There 

 appears to be a marked hyperaesthesia. Usually the first indica- 

 tion of the disease is a partial paralysis of one or both hind limbs. 

 This gradually advances until the rabbits are completely pros- 

 trated, the only evidence of life being a slight respiratory move- 



