The Function of Hormones in regulating Metabolism . 1 
BY 
HENRY E. ARMSTRONG 
AND 
E. FRANKLAND ARMSTRONG. 
I T has long been known that a variety of substances which are generally 
regarded as chemically neutral are powerful stimulants of vital activity 
if used in very minute proportions but potent lethal agents if allowed to 
operate in larger amounts. Few botanists are unaware of the destructive 
effect that is exercised on plant tissues by the common anaesthetic chloro- 
form and of the use that is made nowadays of hydrocarbons, such as toluene 
and naphthalene, as ‘ sterilizing ’ agents ; the acceleration of the flowering 
processes in plants and of the ripening of fruits by means of ether vapour 
may also be cited as familiar cases of stimulative action : we have been 
led to study the effects produced by such neutral substances in the hope of 
arriving at an explanation of their phenomenal activity. In a recent 
communication to the Royal Society we have described and discussed experi- 
ments made with Primus Laurocerasus in which leaves of this shrub were 
exposed to a variety of vapours and solutions in presence of Guignard’s 
alkaline picrate paper ; this test affords a means of detecting minute quan- 
tities of hydrogen cyanide, the yellow paper becoming orange and ultimately 
brick-red under the reducing influence exerted by this compound. 2 When 
a substance enters the leaf and conditions hydrolysis of the cyanophoric 
glucoside Prulaurasin (PhCH(CN),0.C 6 H n 0 5 ), which the leaf contains, 
the intrusion is indicated by an escape of hydrogen cyanide. As the change 
that is initiated by the entering substance is cumulative, for reasons that 
will be apparent later on, a minute proportion of substance produces 
a relatively large effect ; the test, therefore, becomes one of extraordinary 
delicacy. 
The title of our communication 3 may be referred to as an indication, 
in our opinion, that the inquiry is one in which many issues are to be con- 
sidered. 
1 Studies in Enzyme Action XIV ; for XIII, see Roy. Soc. Proc., B., lxxxii, 1910, pp. 349-67. 
2 Cp. A. C. Chapman, The Analyst, 1910, with reference to limitations, pp. 35, 269. 
3 The Origin of Osmotic Effects. III. The Function of Hormones in stimulating Enzymic 
Change in relation to Narcosis and the Phenomena of Degenerative and Regenerative Change in 
Living Structures. Roy. Soc. Proc., B., lxxxii, 1910, pp. 588-602. 
[Annals of Botany, Vol. XXV. No. XCVIXI. April, 1911.] 
