[Vor. 4 
214 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
lighter areas of diseased leaves than in the darker. If the 
metabolism of the cells of the lighter areas is such as to ar- 
rest the formation of formaldehyde, the formation of unusual 
enzymes might take place which, when introduced into a 
normal healthy individual, are capable of reproducing them- 
selves and stimulating a pathological condition in a manner 
which will be described later. 
Dried and ground mosaic material was next treated with 
various organic extractives. Ten grams of dried material 
were treated with 70 сс. of the extractive for 2 days. At the 
end of this time the extractive was filtered off and evapo- 
rated at room temperature. Inoculations were later made 
with water suspensions of the residue obtained after the 
evaporation of the extractive, and also with water extracts 
of the material which had previously been treated with the 
extractives. The extractives used were ether, chloroform, 
earbon tetrachloride, toluene, acetone, ethyl alcohol, methyl 
alcohol, and glycerin. No infections (with one exception) 
resulted when inoculations were made with the water sus- 
pension of the residue obtained after the evaporation of the 
extractive. This exception was that of glycerin. In this case, 
however, the residue had been macerated with the extractive, 
and Allard later found that if the glycerin was simply allowed 
to act on the dried mosaic material and was then poured off, 
it contained little, if any, of the infectious principle. When 
inoculations were made with the water extract obtained from 
material which had been previously treated with various ex- 
tractives, infections resulted in all cases except in those 
where alcohol had been used. 
All this is entirely in accord with what one would expect if 
we were dealing with an enzyme. If the infectious substances 
were of the nature of an organism, it certainly should have 
been destroyed by treatment for 2 days with concentrated 
solutions of such antiseptics as ether, chloroform, carbon 
tetrachloride, acetone, toluene, and glycerin. It also lends fur- 
ther proof to the contention that in the case of treatment with 
formaldehyde the destruction of the infectious substance 
was due, not to the antiseptic properties of formaldehyde, but 
