1918] 
BONNS—ETHERIZATION AND ENZYME ACTIVITY 259 
and Guignard (709). The stimulative action of various 
volatile substances was noted, as well as the effect of solu- 
tions of electrolytes and non-electrolytes. Observations 
showed that all substanees which were able to penetrate the 
cell membrane acted as stimulants to varying degrees. The 
most active stimulants were those with little, if any, chemical 
activity, and which have very slight attraction for water,— 
i. e., they are anhydrophilie. It was also shown that hydrogen 
cyanide or benzaldehyde,—two of the products of prulaurasin 
hydrolysis,—had a cyanogenetic effect upon the leaves similar 
to that of the other vapors studied; hence the Armstrongs 
concluded that the action of the penetrating substances could 
not be primarily a chemical one, since it could be effected by 
some of the products resulting from the hydrolysis itself. The 
stimulation produced by chemically inactive vapors is ascribed 
to their action in causing changes in the concentration of 
the cell solution of such nature that the glucoside and the 
enzyme are brought into contact under conditions which pro- 
mote hydrolysis. All substances which enter the cell effect 
such concentration changes to some degree. In the case of 
substances in solution the water entering with the solute is 
probably a factor in altering the concentration of the cell 
fluids. It is evident that this theory is based upon the as- 
sumption of a purely ‘‘mechanical’’ activity on the part of 
the stimulating agents, as a result of which the concentra- 
tion is lowered to a point which is either favorable to a 
change previously existing only in a potential state, or is 
more favorable to an action already occurring. 
The effect of the same stimulating substance acting as a 
narcotic or lethal agent is ascribed to changes in the osmotic 
pressure. Assuming an active cell, the pressure varies con- 
tinually as carbon dioxide and other simple compounds are 
removed from solution and combined in more complex forms. 
With their disappearance others diffuse in from without. The 
more complex molecules are in part more or less inactive 
by incorporation in the protoplasmic mass, but some have a 
marked attraction for water. The products of the ‘‘down- 
grade” changes which occur at the time of synthetic trans- 
