292 DISEASES OF TRUE INFECTION 



the animal had ])een killod. Galticr noticed the same conditions in the 

 decayed brain substance of a rabid dog, when kept under a low tempera- 

 ture (12° Celsius). An affected brain was not rendered harmless even 

 when exposed for three weeks at a time, but its virulence was attenuated 

 wdien kept some time at a temperature of 61° Celsius. Bluml)erg found 

 that an affected brain is rendered harmless when it has undergone a freez- 

 ing process at 20° or 30°. Galtier was able to destroy the virulence of af- 

 fected cerebral matter in four to twenty days by placing it upon plates and 

 allowing it to become dry. Saliva and blood are much less resistant than 

 brain matter. Both su])stances as a rule, lose their harmful properties 

 twenty-four hours after leaving the animal. Dried saliva is inactive 

 fourteen hours after it comes from the mouth of the animal, the gastric 

 juice destroys it in five hours; bile kills it in a few minutes, and it is de- 

 stroyed quickly by corrosive sublimate, chlorine water, permangate of 

 potash, sulphuric acid, creolin, etc. The X-rays seem to retard the 

 development of the virus. 



As a rule, it is necessary to make a natural or artificial inoculation in 

 order to obtain any successful transmission of the rabid poison, as no in- 

 fection will take place if an animal is given the saliva, flesh, brain or spinal 

 cord of an affected animal, or if the inoculation is simply rubbed on the 

 cutaneous or mucous membranes; but if the mucous membrane is scarified 

 first it can be reproduced. The most certain method to reproduce the 

 disease is to introduce the virus directly on the dura mater of the brain 

 or spinal cord, or in the anterior chamber of the eye. Heredity — that is, 

 transmission of rabies by the mother to puppies or the production of the 

 disease by infected saliva being in food — is very questionable. The most 

 common method, of course, is the bite of the rabid animals; more rarely 

 licking of a wound. In many cases the bite may not be severe enough to 

 cause its development in dogs or in man. Deep bites, however, are 

 certainly the most dangerous, especially when made on the unprotected 

 parts of the body (hands and face in man). Wounds which bleed much 

 are less dangerous, as the poison may be washed out of the wound by the 

 flowing blood. Bites of dogs which have bitten numerous others are 

 less dangerous than the first or second bite made by a rabid animal. 



Infectious wounds which were made by biting or inoculation, accord- 

 ing to Hertwig's observations, showed only 37 per cent, of positive results, 

 and Renault's 67 per cent. Of 137 animals which were bitten by rabid 

 dogs under observations for the last five years at the Veterinary College of 

 Berlin, six only ultimately developed the disease. Zundel finds that 

 about 25 per cent, of inoculated animals become affected, while Haubner 

 found 40 per cent. At Alfort they have found the proportion to be about 

 33 per cent., and at Lyons, 26 per cent. In man 50 per cent, of the 

 bitten subjects develop the disease, but if we sum together the cases of 



