HYDROPHOBIA. 321 



HYDROPHOBIA (LYSSAj RABIES). 



The exciting agent of hydrophobia is not yet known. 

 Nevertheless, the specific treatment of this disease has been 

 successful, owing to the genius of Pasteur. 



The susceptibility for hydrophobia exists among all 

 warm-blooded animals. Human beings are infected through 

 the bites, in the first place, of rabid dogs, then of cats, 

 wolves, foxes, jackals, and other animals, and, in rare 

 cases, of human beings suffering from hydrophobia. The 

 saliva must thus contain the virus of the disease, and as a 

 matter of fact this had already been demonstrated experi- 

 mentally at the beginning of the last century by inocula- 

 tion of dogs from human beings. The parotid is the gland 

 most concerned, while the remaining salivary glands, 

 though virulent, are not so constantly so as the parotid. 

 The saliva of dogs contains the virus of rabies as early as 

 two days before the appearance of the first symptoms of 

 the disease. The lacrimal glands, the adrenal glands, the 

 pancreas, and the mammary glands of rabid animals are 

 further infectious ; the milk, at times is so ; the blood, never. 

 Besides, the central nervous system is virulent the brain 

 and the spinal cord and, in a conspicuous and constant 

 manner, the medulla oblongata. 



Experiments on Animals. The saliva is not used for 

 inoculation-experiments because, in addition to the virus 

 of rabies, it always contains a number of pyogenic micro- 

 organisms that act as a disturbing factor. The medulla 

 oblongata of animals or individuals that have died of rabies 

 is used exclusively for inoculation-purposes. A wateiy 

 emulsion is made from a small portion of the medulla ob- 

 longata, and a few drops thereof are injected beneath the 

 dura mater or into the anterior chamber of the eye in 

 dogs, rabbits, etc. After a period of incubation of from 

 twelve to fifteen days the animals develop, with almost 

 absolute certainty, the symptoms of rabies. Subcuta- 

 neous injection is not quite so trustworthy. In order 

 to obtain positive results the injection must be made 

 deeply, and preferably into the exposed and divided 

 muscle-bundle. Direct injection of the virus into a periph- 

 eral nerve is likewise attended with success. Healthy 

 mucous membranes (as of the nose and the conjunctiva) 

 also absorb the virus. The possibility of intrauterine 



