3l6 RABIES 



Certain investigators however have found histological 

 •changes, which to their minds have been pathognomonic of the 

 disease. The close simulation of the nervous lesions to those 

 due to other diseases, and the possibility of greater or less post- 

 mortem changes will foster an element of doubt in the minds 

 -of the majority of working histologists. This doubt instead 

 of diminishing shows a tendency to grow when a review is 

 taken of the conflicting results and opinions held by those who 

 have already investigated this field. It also appears that some 

 portions of the nervous system may exhibit lesions of a pro- 

 nounced character, other portions very slightly, and still 

 others none at all, thus presenting additional difficulties. 



One of the most common lesions that has been observed is 

 of an inflammatory character, the congested blood vessels fre- 

 quentl}' showing diapedesis and, according to some, a perivas- 

 cular exudation of a granular or hvaline substance. HvDere- 

 mia and lymph-stasis, although of not so much significance 

 when taken bj' themselves, have been taken into considera- 

 tion along with other changes. The blood vessels quite as 

 much or even more than the nerve structures have been noted 

 as the locus of some of the most marked changes, among 

 which are the proliferation of the epithelial cells and of the 

 connective tissue elements of the outer coat, with the infiltra- 

 tion by lymphoid cells. Such lesions may be nodular pri- 

 marily, but later become diffuse. The inflammatorj^ proces- 

 ses may progress to such an extent as to obliterate certain 

 vessels. 



Pathological miliar}' centers have been noted not only in 

 the axial portions of the nervous sj'Stem, but in the gray 

 matter as well. These centers are formed by lymph cells 

 which accumulate notably around the blood vessels (perivas- 

 cular) and the nerve cells (pericellular) as well. The lesions, 

 when present, are observed most frequently in the motor cen- 

 ters of the oblongata and spinal cord. 



The following observations were made b}- Babes, in 1887 : 



I. "In animals dead from street rabies there are found 

 usually a hyperaemia and an acute generalized cedema of the 

 cerebral meninges, acute hemorrhages localized around certain 



