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exanthem of variola vera in man. As has been pointed out, the specific 
lesions of variola inoculata in the monkey differ from the lesions of the 
exanthem in variola vera in man in the greater prominence of the 
polynuclear leucocytes in the former. The primary lesions of variola 
inoculata in the monkey differ from the vaccine lesions of that animal 
in the extent and character of the process in the corium beneath the 
lesion, it being more intense in variola inoculata. 
It is evident that the lymph spaces of the skin are flooded with virus 
at the time of the inoculation, and this fact may be a factor in the early 
development of the exanthem in the inoculated disease. From the fact 
that cytoryctes are demonstrable in the endothelial cells of the capillaries 
in the corium beneath a primary lesion of five days’ duration, it seems 
probable that at the time of inoculation, cells of this type become 
infected. Such infected cells in the lymph spaces or in the capillaries 
might easily be swept away in the circulation, and lodging in skin 
capillaries become the focus for an exanthem. 
The absence of focal lesions in the bone marrow and testicles in 
variola inoculata in the monkey emphasizes the difference already men- 
tioned between the disease experimentally produced in the monkey and 
variola vera in man. 
CONCLUSIONS. 
(1) Inoculation of the skin of the monkey (M. cynomologus and M. 
nemestrinus) with variola virus produces a disease in which all the 
essential characteristics are identical with those of variola inoculata in 
man. 
(2) Variola noculata in the monkey differs from variola inoculata in 
man in that the fever has a shorter duration and the exanthem appears 
at an earlier date. 
(3) Vartola inoculata in the monkey is as distinct a clinical entity 
as is variola moculata in man. 
(4) Cytoryctes variole are found in the endothelial cells of the capil- 
laries in the corium beneath the primary lesion of variola inoculata. 
2. VARIOLA INOCULATA IN THE ORANG-UTAN. 
Introduction.—VThe experiments here reported were performed to deter- 
mine the reaction of the orang-utan to inoculation with variola virus 
and to obtain material for the microscopic study of the specific lesions 
and of the morphology of the causitive organism in this species of animal. 
Four orang-utans were procured for this work, but unfortunately only 
two of them survived long enough for the experiments to be carried out. 
These experiments are the first in which anthrapoid apes have been used 
as the experimental animal in a study of small pox. The systematic 
position of the orang-utan in the animal kingdom makes it of peculiar 
*Magrath and Brinckerhoff: Jour. Med. Research, 11, 230. 
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