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The histological peculiarities of the specific lesion of vaccinia in these 
monkeys are similar in every way to those found in lesions following vac- 
cination of other susceptible animals. 
We have seen then that the disease vaccinia in M. cynomologus con- 
forms strictly to the type of the disease vaccinia and in a more general 
way can be included in that group of processes which embraces all forms 
of variola and vaccinia. 
The data furnished by our experiments upon the immunity reactions 
and upon the differences due to different strains of virus will be presented 
in another section of this article. 
CONCLUSIONS. 
(1) Inoculation of the skin of M. cynomologus with vaccine virus is 
followed by the development of a lesion at the site of inoculation which 
is stmilar in all respects to that which follows similar inoculations of 
other animals. 
(2) The development of the lesion is associated with a rise in the body 
temperature which is most marked during its active evolution. 
(3) The lymph nodes which are interposed between the area of skin on 
which the lesion develops and the main lymph trunks, show enlargement 
coincidently with the temperature reaction. The nodes show histological 
changes which account for this enlargement. 
(4) Cytoryctes variolew is found in the epithelial cells of the vaccine 
lesion and also in the endothelial cells of capillaries beneath the epithe- 
lium of the lesion. 
(5) Macacus cynomologus is susceptible to vaccinia. 
2. VACCINIAL KERATITIS IN THE MONKEY. 
Nine monkeys were inoculated and the animals were killed after vari- 
ous periods to obtain material for the histological study of the lesion at 
different stages of its development. 
Technique-—The animal was deeply anesthetized and the cornea 
lightly incised with a sharp scalpel. Care was taken not to cut deeply 
into the corneal substance. A small amount of vaccine was rubbed into 
the incision. A daily record of the appearances at the site of inoculation 
and of the general condition of the animal was kept. When the animals 
were killed a complete autopsy was done, and tissue for histological study 
was saved from the site of the specific lesion and from the viscera. The 
animals were under the influence of morphine during the development of 
the lesion. 
EXPERIMENTS IN DETAIL. 
No. 13. Monkey inoculated on both corneas with vaccine virus No. 1. After 
17 hours the cornea shows no macroscopic evidence of a specific process. Animal 
chloroformed and tissues preserved for histological study. 
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