Nature of the Disease 413 



the diseased to take water because of painful spasms caused 

 by the attempt. 



This brief description will suffice to illustrate a parallel- 

 ism existing between hydrophobia and tetanus. In both 

 affections we observe the entrance of infectious material 

 through a wound, which 'sometimes heals, but often sup- 

 purates a little. We see in both affections an' incubation 

 period of varying duration, though in hydrophobia it is 

 much longer than in tetanus, and in both there occur con- 

 vulsions of tonic character, causing death from asphyxia. 



It is maintained by some that the stage of excitement 

 argues against the specific nature of the disease, and that 

 it is essentially hysteric ; but these subjective symptoms are 

 like the mental condition of tuberculosis, which leads the 

 patient to make a hopeful prognosis of his case, and the 

 mental condition of anthrax, in which it is said that no 

 matter how dangerous his condition the patient is seldom 

 much alarmed about it. 



Pasteur * and his co-workers, Chamberland and Roux,f 

 found that in animals that die of rabies the salivary glands, 

 the pancreas, and the nervous system contain the infection, 

 and are more appropriate for experimental purposes than 

 the saliva, which is invariably contaminated with accidental 

 pathogenic bacteria. 



The introduction of a fragment of the medulla oblongata 

 of a dog dead of rabies, beneath the dura mater of a rabbit, 

 causes the development of typical rabies in the rabbit in 

 about six days. It is only by such an inoculation that a posi- 

 tive diagnosis of the disease can be made. The operation must 

 be performed with the greatest care in order to avoid septic 

 infection with meningitis. The technic is simple, a small 

 trephine for opening the rabbit's skull being obtainable from 

 the dealers, though in its absence the thin bone of the cranial 

 cavity may be cut with a heavy scalpel. The material to be 

 inoculated should be crushed to a fine pulp in sterile physio- 

 logic salt solution, and introduced beneath the dura with a 

 hypodermic syringe. The tissue of the medulla of a rabid 

 rabbit introduced beneath the dura mater of a second rabbit 

 produces a more violent form of the disease in a shorter 

 time, and by frequently repeated implantations Pasteur 

 found that an extremely virulent material could be obtained. 



* " Compte-rendu Acad. des Sciences," Paris, 1889, cvm, p. 1228. 

 f Ibid., Oct. 26, 1885. 



