H. W. Acton and W. F. Harvey 
261 
well marked central vacuole and as they grow large a secondary vacuole 
appears. In the largest Negri bodies a large central vacuole, surrounded 
by numerous secondary ones, is to be seen (PL XI, fig. 4). The 
nucleolus of these nerve cells may be multiple and generally takes 
Mann’s stain or as the case may be Van Gieson’s. 
(iv) Ooat. The Negri bodies are small (1 to 6/r) and scattered 
among the ganglion cells of the Ammon horn. They are ovoid in shape 
and usually exhibit one vacuole. In the cells of the fascia dentata, of 
this animal as well as the bullock, small Negri bodies are seen varying 
from 1 to 4 yu. in size and round in shape. 
(v) Monkey. The Negri bodies are small (1 to Q y) and homo¬ 
geneous. In a rabies-infected monkey that died on the 12th day of 
incubation from intussusception {i.e. a very early case of rabies) the 
Negri bodies were situated close to the nuclei, giving an appearance as 
if they had just been extruded from it. The tangential and circum¬ 
ferential fibres of the nerve cells were fragmented, giving rise to a fine 
punctate appearance of the extra-cellular ground substance. It is this 
punctate appearance, due to fragmentation of fibres, which may explain 
the fine chromatoid peppering found in rabies brains by some observers. 
In the cerebellum, the Negri bodies were large (6 to 12/r). They all 
stained red with the Van Gieson mixture. No yellow masses were seen 
in the cortical cells. 
(vi) Rabbit. In this animal the Negri bodies are all exceedingly 
small, varying from ^ to 2 p, in size and generally 2 to 5 are seen in 
the cell. They appear homogeneous in structure, and stain by Van 
Gieson’s method (PI. XI, figs. 5, 6). The nucleoli of the cells are 
markedly fragmented, and generally stain red or terracotta. 
(vii) Guinea-pig. This is the animal par excellence in which to 
study Negri bodies, and it was the observation of the appearances found 
in test animals, that led us to commence this study on the nature of 
these bodies. Here one at once recognised the close similarity in 
appearance of Negri bodies to the cap-shaped archoplasmic vesicle 
found in the sperm cells of this animal. Our studies of the Negri 
bodies in guinea-pigs were especially large and extended to over 100 
animals. In the ganglion cells of the hippocampus major, Negri bodies, 
very large for the size of tlie animal, are seen, varying in size from 4 to 
Ifiya (PI. XI, fig. 9). They are round or ovoid and usually situated 
near the nucleus. With careful focussing it will be found that they are 
indented on the nuclear sidevand appear as if they gripped the nucleus. 
The larger ones may show an indefinite lighter stained centre, but no 
