PATHOLOGY OF HYDROPHOBIA. 507 



The Pathology of Hydrophobia. In hydrophobia as in 

 tetanus, to which it bears more than a superficial re- 

 semblance, the appearances presented in the nervous 

 system, to which all the symptoms are naturally referred, 

 are comparatively unimportant. On naked-eye examination, 

 congestions, and, it may be, minute haemorrhages in the 

 central nervous system, are the only features noticeable. 

 Microscopically, leucocytic exudation into the perivascular 

 lymphatic spaces in the nerve centres has been observed, and 

 in the cells of the anterior cornua of the grey matter in the 

 spinal cord, and also in the nuclei of the cranial nerves, 

 various degenerations have been described. The latter 

 include pigmentation, atrophy, and vacuolation of the 

 protoplasm, and the occurrence of a deposit of granules in 

 the nucleus. In the white matter, especially in the posterior 

 columns, swelling of the axis cylinders and breaking up of 

 the myeline sheaths have been noted, and similar changes 

 occur also in the spinal nerves, especially of the part of the 

 body through which infection has come. In the nervous 

 system also some have seen minute bodies which they have 

 considered to be cocci, but that they are really such there 

 is no evidence. The changes in the other parts of the 

 body are unimportant. 



Experimental pathology confirms the view that the 

 nervous system is the centre of the disease by finding 

 in it a special concentration of what, from want of a more 

 exact term, we must call the hydrophobic virus. Earlier 

 inoculation experiments made by subcutaneous injection 

 of material from various parts of animals dead of rabies 

 had not given uniform results, as, whatever was the source 

 of the material, the disease was not invariably produced. 

 Pasteur's first contribution to the subject was to show 

 that the most certain method of infection was by inserting 

 the infective matter beneath the dura mater. He found 

 that in the case of any animal or man dead of the disease, 

 injection by this method of emulsions of any part of 

 the central nervous system, of the cerebro- spinal fluid, 

 or of the saliva, invariably gave rise to rabies, and also that 



