606 RABIES AND THE NEGRI BODIES 



more inner bodies having a more or less complicated and regular 

 structure." Negri early recognized that the rabies bodies in the gan- 

 glion cells of the brain had a nucleus, and he later stated that their 

 chromatin had either a solid or a reticular structure, while their 

 cytoplasm contained a variable number of chromatin granules. The 

 latter are frequently arranged, as stated by Williams and Lowden, in 

 a more or less complete circle about the nucleus. They are somewhat 

 irregular in outline and size, being occasionally ring-shaped, some- 

 times elongated, often in twos, due probably to the ative changes 

 of growth and division. The difference in shape of the Negri bodies, 

 such as round, triangular, etc., is due to their position in the ganglion 

 cells, since their bodies are very plastic and easily adaptable to a 

 variety of positions. The variability in shape is also probably largely 

 due to a rapid multiplication. The division forms suggest rapid 

 growth and multiplication. The elongated forms, containing from 

 two to five or even six nuclei, are the result of rapid nuclear division 

 without corresponding cell division. This condition is found quite 

 frequently in protozoa. The elongation of the protoplasm is probably 

 due to the position of these bodies between the nerve fibrils, and to 

 their great plasticity. 



Under the most favorable conditions (fixed virus), growth and 

 division occur most rapidly and simply, the tiny forms dividing and 

 redividing apparently indefinitely. Small mulberry masses are found 

 during this stage, but whether they are the result of the breaking up 

 of a larger form or of the rapid division of a tiny form it is impossible 

 as yet to say. 



In cases where there has been an inoculation of comparatively 

 small quantities of the virus, i. e., a small number of forms of the 

 parasite capable of immediate infection, or in cases where there has 

 been an infection of less susceptible animals (dogs, cattle, human 

 beings, etc.), or with a less accustomed virus (fixed virus of rabbits 

 into guinea-pigs or mice), a slower growth is obtained with its larger 

 structures and different division forms. The chromatin accumu- 

 lation in the form of a definite nucleus apparently undergoes frag- 

 mentation very easily, resulting in forms containing two to several 

 central bodies, some rounded, some elongated, some of unequal 

 division similar to budding. Then forms are found with bodies 

 apparently differentiated within one membrane, and bodies with 

 practically all stages of hour-glass constriction, indicating transverse 

 division. Many pairs, unequal in size, apparently fusing or dividing, 

 have been seen, and finally, large bodies with the chromatin scattered 

 throughout the whole organism in the form of tiny, unevenly rounded, 

 or elongated masses. One or two will be larger, indicating the remains 

 of the nucleus. In these forms are found all stages of apparent 

 budding, varying somewhat in size, some being very tiny. The 

 formation of buds accounts for the appearance in the same cell of 

 both large and small forms. It also helps to account for the rapid 



