Mo. 6. DEPARTMENT OF AGRICULTURE. 52S 



latioii beneath the membranes of (he brain. For this purpose a 

 small button of bone is taken from (he skull, just large enough ta 

 admit the insertion of a hypodermic needle, and three or four drops 

 of a suspension of the brain, made by I'ubbing with water in a 

 mortar, is introduced. The wound in the skin is washed with car- 

 bolic acid and (hen sealed with collodion and cotton. The rabbit 

 shows no inconvenience from the operalion whatever, and will eat 

 and play within a minute after its completion. If the operation is- 

 done in a cleanly manner, and the material is fresh and has not under- 

 gone decomposition at all, no ill effects are observed until symptoms 

 of h3drophobia present themselves. This seldom occurs in less 

 than three weeks, and may not take place until sixty days have 

 passed. The symptoms as seen in the rabbit are well defined and 

 entirelv diagnostic. The form of the disease in rabbits after such 

 inoculation is almost always the paralytic, though at times the 

 animals become furious, biting a stick or any other object within 

 their reach. Before the death of the animal its symptoms are care- 

 fully noted, and after its death the brain and organs are examined, 

 and cultures made from the blood and all organs, with the object 

 of making sure that the animal died of hydrophobia, and not of some 

 accidental infection, in which case the germ producing that infec- 

 tion would be manifest in the cultures. When the inoculated animal 

 dies before the fourteenth or fifteenth day we may be reasonably 

 sure that it has not died of rabies, but as a result of the operation. 

 This examination can be carried out properly only by those who have 

 had special training, and should not be attempted by others. 



Microscopic Examinatiox. In a disease marked by such striking 

 symptoms referable to the nervous system, it is natural to expect 

 that changes w'ould be found in the central nervous system suf- 

 ficient to account for the production of symptoms. As well stated 

 by Babes, ''this disease so clearly characterized by a train of symp- 

 toms, constant in their character, ought also to present character- 

 istic lesions in the nervous centers, and especially in the ganglia 

 which preside over the production of symptoms." Numerous studies 

 have been undertaken by workers in various parts of the world, 

 with the object of discovering some change in the nervous system 

 which could be considered as belonging especially to rabies, but 

 while changes were found, none of them could be considered as 

 specific. 



Recent Advances in our Knowledge. During the year 1900, the 

 discovery of changes distinctive of rabies was announced by Van 

 Gehucten and N^lis. These changes are found in the peripheral 

 ganglia of the cerebrospinal and sympathetic systems, and are 

 especially marked in the ])lexifor]n ganglion of the pneumogastric 

 nerve and the gasserian gangli(»n. Normally, these ganglia, are 



