[Vor. 4 
194 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
elapsed between the time that the material was gathered and 
the time when inoculations were made. 
As has already been stated, no infections resulted from 
these inoculations, and the experiment is of absolutely no 
value as far as throwing further light upon the transmis- 
sibility of cucumber mosaic to other cucurbits; but it does 
afford the writer an opportunity to criticize the technique in- 
volved, to point out probable sources of error, and to lay 
special emphasis upon the amount of care which must be ex- 
ercised when dealing with something, the nature of which is 
so incompletely known. 
If the infective principle is of the nature of an organism, 
one can easily see how the parasite might have been destroyed 
mechanically during the maceration of the tissue. Fred (716), 
for example, has been able to reduce the number of bacteria 
in 1 gram of dry soil from 2,000,000 to 400,000 by grinding for 
1 hour. In another instance the number was reduced from 
3,194,000 to 75 by grinding for 24 hours. 
Allard (716%) found that the ‘‘virus’’ was extremely sensi- 
tive to the antiseptic properties of formaldehyde. Warner 
(214) has demonstrated that formaldehyde is one of the ox- 
idation products of chlorophyll extracts. The loss of the in- 
fectious properties of the cucumber extract used for inocu- 
lating might, in the absence of any proof whatever, be ac- 
counted for in this manner. 
If the infective principle is of the nature of an enzyme or 
colloidal substance it is also possible, as with bacteria, that 
destruction took place through mechanical agitation. It is a 
well-known fact that many colloids, especially suspensoids, 
are thrown out of the colloidal equilibrium by mechanical 
agitation. This fact was furthermore demonstrated by Brown 
(715) working on the macerating and lethal enzymes of 
Botrytis cinerea. He found that this action could be reduced 
eight-ninths by simply bubbling air through the extract for 
45 minutes. Allard (716%) also found that the ‘‘virus’’ was 
greatly adsorbed by tale. Whether or not the adsorptive 
power of the asbestos used, coupled with centrifugation, can 
account for the removal of the infective principle from the 
