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However, in the corium the process of cedema and necrosis is lacking, but 
there is some degree of cell reaction evidenced by the enlargement and 
proliferation of endothelial cells. The emigration of polymorphonuclear 
leucocytes is a prominent feature of the process. 
(c) The lymph nodes associated with the primary lesion show a 
marked reaction, consisting in proliferation of endothelial cells in the 
sinuses and in the follicles and in the active phagocytic properties of 
these cells. The presence of red blood corpuscles and of polymorpho- 
nuclear leucocytes in the sinuses and the small areas of hemorrhage in 
the follicles appear also to be a part of the process. 
(d) The internal organs show nothing which can be interpreted as 
manifestations of the disease produced in the animal by the inoculation. 
DISCUSSION. 
We have seen that the inoculation of the skin of the monkey with 
variola virus brings about a disease which exhibits characters at once 
relating it to variola in man and to vaccinia in man and in animals. The 
disease which follows an inoculation of the skin of the abdomen of 
Macacus cynomologus with fresh variola virus consists essentially in— 
(1) The development of a lesion at the site of inoculation. 
(2) The appearance of a general cutaneous eruption of vesicular 
lesions. 
(3) The enlargement of lymph nodes in the axilla and groin. 
(4) The constitutional reaction. 
When we examine the primary lesion microscopically we find it to be a 
self-limiting process which passes through certain definite phases which 
are reflected in the gross appearances and are described as vesiculation, 
pustulation, and crusting. 
When we turn to the lesions of the exanthem we find that the char- 
acteristic phases of the primary lesion are produced in them. 
As we have said, the disease presents a series of characteristic phe- 
nomena, and when a number of animals are simultaneously inoculated we 
see that these phenomena bear a definite time relation to one another. If 
we emphasize this time element we find that the phenomena of the disease 
occur as follows. “ 
The evolution of the primary lesion covers a period of about 14 days 
from the time of inoculation. The first portion of this period comprises 
the active evolution of the local process. This period of active growth 
terminates on about the seventh day of the disease. It is difficult exactly 
to say when the lesions stop developing, but after combining various obser- 
vations, this date is selected as the probable average time for the acme 
of the active evolution of the primary lesion. During the remainder of 
the period the phenomena of repair are dominant in the lesion. 
The general exanthem appears in the majority of cases on the eighth 
