SOME OBSERVATIONS ON THE VIRUS OF VACCINIA 303 
and successful skin inoculations hâve been obtained from tbe 
tbird transfer. 
The virus bas remained active after 34 days incubation, and 
this does not represent the limit of activity under such cul¬ 
tural conditions. 
The method of tissue cultivation is adaptable for the démon¬ 
stration of immunity reactions in vitro. À rabbit was immu- 
nized by a cutaneous inoculation of virus, resulting in an 
extensive eruplion. Two weeks later lhe plasma and cornea 
were used in tbe following experiment. Two sériés of prépara¬ 
tions vvere made, one with plasma and cornea from the immune 
rabbit; tbe otlier, wilh plasma and cornea from a normal rabbit 
(controls). Inoculation of incubâted immune préparations gave 
a completely négative resuit , while similar normal or control 
préparations gave a confluent éruption. 
A second sériés of experiments was carried out, in which 
virus tissue préparations were put up consisting of immune 
plasma and immune cornea, immune plasma and normal 
cornea, normal plasma and immune cornea, and Controls of 
normal plasma and normal cornea. The resuit indicated that 
the greatest lytic action occurred in preparalions containing 
immune plasma and immune corne, next immune plasma and 
normal cornea. The immune cornea with tbe normal plasma 
exerted a slight lylic action. The experiment of testing the 
immunity of the cornea after inoculation of the cornea with 
tbe virus in vivo , bas not been done as yet. 
Whole incubated préparations, containing tissue and plasma 
were inoculated on the rabbit, also vaccinations were made of 
the tissue and of tbe plasma, and it was found that almost ail 
of tbe virus was local ed in the tissue, very little growing or 
surviving in the plasma, indicating the close association of the 
virus with tissue cells. 
In some experiments pièces of paraffm were substituted for 
the cornea and afler incubation, inoculation on a rabbit, 
showed the virus to bave nearly died out. Similar results were 
obtained when pièces of heart, liver or kidney were used. 
There was no evidence of growth, but a graduai weakening 
and death of the virus. 
