1918] SINNOTT—FOOD RESERVE 163 
starch was converted directly into fat or fat directly into starch, 
but as microchemical methods have been employed almost en- 
tirely this cannot well be proven. The only work involving a 
quantitative analysis, that of NrkKLEWSKI (3), seems to indicate 
that changes in the two types of reserve food occur independently 
of each other. It has been observed that the seasonal changes are 
most marked in twigs and small branches, less so in main stems, 
and least of all in roots, where fat is scarce and starch persists 
practically unaltered throughout the winter. The work of Fas- 
RICIUS (1) seems to indicate that in the large trunks of spruce 
conditions may be different from those in small trunks, branches, 
and twigs, and that starch there may have its maximum in winter 
and fat its maximum in summer. 
That temperature is of importance in producing changes in the 
character of the food reserves is shown by the fact that starch 
regeneration may be induced in the winter by bringing twigs from 
out-of-doors into a warm place. That a subjection to cold during 
the summer will not cause the characteristic winter changes, how- 
ever, and that these changes will nevertheless occur in the fall, even 
though the plants remain under a warm environment, indicate that 
factors other than temperature must be operative. 
The present paper is an attempt to throw light on this general 
problem by a careful anatomical study of the storage regions of 
woody plants with a view to determining the exact distribution of 
starch and fat there and its change from season to season. It 
contains the results of nearly three years’ observations on about 
300 species of trees and shrubs belonging to over 100 genera and 
including all the common species of the northeastern United States, 
together with many exotic ones in the collections of the Arnold 
Arboretum. With the exception of a little received from the 
southern states, all the material studied was gathered in Massa- 
chusetts and Connecticut. Special attention was paid to conditions 
in twigs and young branches, where seasonal changes are most 
marked. Thin sections of freshly gathered material were cut on 
the microtome and treated with iodine and Sudan III to bring out 
the starch and the fat, respectively. 
