902 DISEASES CAUSED BY FILTRABLE VIRUS 



the free intervals being marked by attacks of terror and nervous 

 depression. Occasionally there are maniacal attacks in which the 

 patient raves and completely loses self-control. Finally, paralysis 

 sets in, ending eventually in death. 



Pathological examination of the tissues of rabid animals and 

 human beings reveals macroscopically nothing but ecchymoses in 

 some of the mucous and serous membranes. Microscopically, how- 

 ever, many abnormal changes have been observed and were formerly 

 utilized in histological diagnosis of the condition. Babes 20 has 

 described a disappearance of the chromatic element in the nerve 

 cells of the spinal cord. This observation has been confirmed by 

 others, 21 but is no longer regarded as pathognomonic of rabies. The 

 same observer has described a marked leucocytic infiltration which 

 occurs about the blood-vessels of the brain and about the ganglia 

 of the sympathetic system. These changes are not found in animals 

 infected with virus fixe and are present only in animals and human 

 beings inoculated with street virus. 



In 1903 Negri 22 of Pavia described peculiar structures which he 

 observed in the cells of the central nervous system of rabid dogs. 

 While present in all parts of the brain, these " Negri bodies" are 

 most regularly present and numerous in the larger cells of the 

 hippocampus major and in the Purkinje cells of the cerebellum- 

 The presence of these structures in rabid animals and man has 

 been confirmed by a large number of workers in various parts of 

 the world, and the specific association of these bodies with the 

 disease is now beyond doubt. In consequence, the determination 

 of "Negri bodies" in the brains of suspected animals has become 

 an extremely important method of diagnosis more rapid and ac- 

 curate than the methods previously known. 



The demonstration of Negri bodies in tissues is carried out as 

 follows: A small piece of tissue is taken from the cerebellum or 

 from the center of the hippocampus major (cornu ammonis), and 

 is fixed for twelve hours in Zenker's fluid. It is then washed 

 thoroughly in water and dehydrated as usual in graded alcohols, 

 embedded in paraffin, and sectioned. The sections are best stained 

 by the method of Mann, as follows: 



30 Babes, Virch. Arch., 110, and Ann. de Pinst. Pasteur, 6, 1892. 

 n Van Gehuchten, Bull, de 1'aead. de med. et biol., 1900. 

 "Negri, Zeit. f. Hyg., xliii and xliv. 



