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If we compare the disease produced in the monkey by cutaneous inocula- 
tion with variola virus with the disease which follows inoculation of that 
animal with vaccine virus we see at once that the processes are closely 
related. They are similar in that a self-limiting lesion appears at the 
site of inoculation, that the development of this lesion is associated with 
more or less constitutional reaction, and that certain lymph nodes 
become enlarged. The disease produced by inoculation with variola 
virus differs from vaccinia in that the primary lesion is usually followed 
by a general cutaneous eruption of lesions similar in many respects to the 
primary lesion and in that the temperature reaction is more abrupt in its 
onset and more intense. 
If we compare the disease produced in the monkey by cutaneous 
inoculation with variola virus with the various manifestations of variola 
in man, we see that the disease produced is more like variola inoculata 
than any of the other forms. In fact the only differences which we find 
between the two lie in the time of occurrence of the general exanthem 
and in the duration of the temperature reaction. Thus, in the monkey 
we have the exanthem appearing on the eighth day of the disease, the 
temperature, which appeared on the sixth day, quickly falling by lysis, 
while in variola inoculata in man the exanthem appears on the eleventh 
and the temperature persists from the seventh to the ninth day. The 
development of the primary lesion and of the exanthem are practically 
the same in both. 
When we compare variola inoculata in the monkey with variola vera 
in man we find that only certain. characteristics of the disease type are 
held in common. 
Different forms of virus, such as vesicle contents, pustule contents, 
and disk, were used for inoculations. On the skin, all these forms of 
virus produced typical primary lesions. However, it is to be noted that 
the nature of the contagium seemed to have an influence upon the 
occurrence and extent of the exanthem. We feel that these differences 
are explainable upon physical grounds and have to do with the reaction 
of the virus to external conditions rather than to any difference in the 
virus which is inherent to different ages of the lesion from which it is 
collected. This question will be taken up in another section of this 
article. 
In the course of our experiments monkeys of all ages and of both 
sexes were employed. We did not observe any difference in the reactions 
of these animals which could be attributed to these factors. The general 
physical condition of the animal did not seem to affect the results of the 
inoculations. 
The histological study of the specific lesions and of the viscera in 
variola inoculata in the monkey adds some details to our picture of the 
disease. We see that the specific lesions are similar in most respects to 
the vaccine lesions of man and of animals, and to the lesions of the 
