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at its height on the seventh day. Copeman notes that the vesiculation 
is more marked in vaccination than in variolation. Reed finds that Cebus 
apella presents vaccine lesions which run a milder course than they do in 
the other monkeys used by him. Several investigators compare the lesion 
produced in the monkey by inoculation of the skin with vaccine virus, 
with that which develops in the calf and speak of them as being identical. 
The constitutional reaction of the monkey to vaccination is mentioned 
by Copeman and said to be less intense than that following variolation, 
at least so far as is evidenced by the body temperature. 
A general exanthem has never been observed to follow inoculation of 
the skin of the monkey with vaccine virus. 
The immunity reactions of the monkey after vaccination have received 
considerable attention. Copeman reports that vaccination of the skin 
of the “Rhoesus” monkey protects against subsequent inoculation of the 
skin with either vaccine or variola virus. De Haan found the same pro- 
tection to be conferred upon Macacus cynomologus by vaccination. 
The protective power of the serum of a vaccinated animal has been 
tested by several workers. Copeman reports that the oxalated plasma of 
a monkey, immune to vaccination and variolation of the skin through 
inoculation, has a slightly modifying effect upon the course of a yac- 
cination in a monkey into whose peritoneal cavity the plasma has been 
introduced. He also finds that the monkey is rendered immune to vac- 
cination by the subcutaneous inoculation of vaccine virus. Reed finds 
that the serum of a vaccinated monkey protects Cebus apella against 
subsequent skin inoculation with vaccine virus. The serum of vaccinated 
calves was not so efficacious in this respect. 
Certain miscellaneous experiments are of interest. De Haan finds that 
vaccine virus tends to die out if transferred too often on one species of 
animal. The fact that he worked in the Tropics may have influenced 
his results. Blaxall and Fremlin show that vaccine virus in the food of 
a monkey may produce lesions in the mouth or may enter the mesenteric 
lymph nodes and be demonstrable there by inoculation of an emulsion of 
the nodes upon the skin of the calf. 
Inoculations of the monkey with variola virus have been undertaken 
by a number of observers. In all cases the ey has been shown to be 
susceptible to the contagium. 
The contents of the specific skin lesion of variola in man has been used 
for inoculation by Zulzer, Copeman, De Haan, Béclére, Chambon, and 
Menard, Roger and Weil, Ewing, Park, and by Magrath and Brinckerhoff. 
As a rule the virus was used in the fresh state, but Zulzer and Park have 
both employed dried virus as well. The blood from a case of hemor- 
rhagic variola was used by Zulzer and by Roger and Weil. 
Inoculation of a scratch or scarification on the skin has been used as 
the mode of introducing the contagium in a majority of the experiments. 
Simple contact with the unbroken skin as well as exposure to dried and 
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