NOTES. 
A CONTRIBUTION TO THE CHEMISTRY AND PHYSIO- 
LOGY OP FOLIAGE-LEAVES 1 : BY HORACE T. BROWN, 
F.R.S., AND G. H. MORRIS, PH. D.— The investigation of which 
we give an account in this paper is an attempt to throw some light 
upon the occurrence, relations, and physiological significance of the 
starch, diastase, and sugars contained in foliage-leaves. 
It originated in an attempt to explain a certain technical operation 
in brewing which had hitherto been purely empirical in its application, 
and to this we may perhaps briefly refer at the outset, as there is 
a certain amount of chemical interest attached to it. 
When the primary fermentation-process is completed and the 
beer has been racked into casks, it has been customary in some 
localities to add to the finished beer a small quantity of dry hops, 
the effect of which is marked in several ways. One very important 
effect is to hasten the secondary fermentation, and thus to produce 
a ‘ briskness ’ or ‘ freshness * in the beer, a fact which has been 
well recognized for generations by the practical brewer, but up to the 
present time has never been satisfactorily explained. 
It is unnecessary to give any details of the investigation which 
led us to a true explanation of this effect of ‘ dry hopping,’ as it is 
called, especially as we have recently treated of it at length elsewhere, 
but we may briefly state that we found it to be dependent upon the 
presence in the hop-strobiles of a small but appreciable amount 
of diastase , sufficient to slowly hydrolyze the non-crystallizable pro- 
ducts of starch-transformation left in the beer, and to reduce them 
to a condition in which they can be seized upon and fermented by 
the yeast. 
It now became a matter of interest to ascertain if this occurrence 
of diastase in the hop-strobile is an isolated case, or a special example 
of a widely distributed property of vegetable tissue. 
1 Abstract of a paper read before the Chemical Society, April . 2.0, 1893. 
