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045 
(e) The effect upon a strain of variola virus of repeated passages through the 
monkey.—No. 200 virus. <A series of 5 monkeys was inoculated with this strain 
of virus, each animal save the first being inoculated with curettings of the 
primary lesion of the previous monkey of the series. Typical primary lesions 
developed on each animal. The exanthem was profuse after the first and second 
serial inoculation, but was sparse in the third and fourth animal. The strain 
was transferred to 2 additional monkeys from the primary lesions of the second 
monkey of the series, and in each of these animals an atypical primary lesion 
developed, but was not followed by an exanthem. After the third serial transfer 
the strain was inoculated on another monkey, yielding an atypical primary lesion 
followed by a sparse eruption. A transfer from the primary lesion of this animal 
resulted in an atypical primary lesion and no exanthem, 
A series of 4 monkeys was inoculated by transfer of virus from the exanthem, 
beginning with the second animal of the first series described. Each animal 
showed a typical primary lesion save the last, in which the process was somewhat 
delayed. A profuse exanthem developed in each animal. 
The strain-was inoculated at each transfer of the above series to another monkey 
and in each case yielded an atypical primary lesion. The first transfer was fol- 
lowed by a moderately extensive exanthem. 
The second animal of the series of inoculations with the virus from the exan- 
them was used as a source of virus for testing the immunity of certain monkeys. 
The contents of the primary lesion was employed. Three animals inoculated 
with this virus developed typical primary lesions, which were followed by a sparse 
general exanthem. 
No. 199 virus. This strain of virus was carried through one orang-utan and 
two monkeys. The first monkey showed a typical primary lesion and a profuse 
exanthem. The second monkey did not react to the inoculation. 
The time of the occurrence and the evolution of the exanthem in.all the 
monkeys of these experiments was similar to that seen in animals inoculated with 
fresh human variola virus. 
SUMMARY. 
(1) A variola virus (vesicle contents and disk) lost its power to 
produce a specific lesion upon the skin of the monkey after prolonged 
exposure to high temperature, to putrefaction, and to desiccation. 
(2) A sample of variola virus lost its power to produce a specific 
lesion on the monkey’s skin and on the rabbit’s cornea by passage 
through the “N” Berkefeld filter. 
(3) A sample of variola virus retained its power to produce a 
primary lesion, but lost its exanthem-producing properties after exposure 
to 60 per cent glycerin for 50 days. 
(4) A strain of variola virus showed less and less power to cause a 
typical primary lesion on the monkey and a waning exanthem producing 
potentiality after repeated passages through monkeys. 
DISCUSSION. 
The reaction of vaccine virus to drying and to the action of glycerin 
has been carefully determined by those who have charge of the prepara- 
tion of vaccine for protective inoculations against smallpox. It is a 
matter of common knowledge that vaccine retains its potency for a 
