284 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1919. 
In most of our wild species of trees and shrubs the reserve carbo- 
hydrate material is stored away during summer and autumn in the 
form of starch. At the beginning of dormancy the twigs and sap- 
wood are gorged with this material, the starch grains being stored 
ordinarily in the cells of the medullary rays and sometimes in the 
pith. As the process of chilling goes on, this starch little by little 
is transformed into sugar. The presence of large quantities of starch 
in the fall and early winter may be observed by applying to freshly- 
cut surfaces of the twigs the well-known starch test of a 2 per cent 
solution of iodine in a 1 per cent solution of iodide of potassium. 
With a strong hand lens the starch is readily observed, if present, 
by the deep blue color it assumes under this treatment. The intensity 
of the coloration gives roughly an idea of the number of starch 
grains present, and thus by this simple means anyone may observe 
in the twigs of trees and shrubs the gradual disappearance of their 
starch as spring approaches. 
The measurement of the increasing amount of sugar is more 
difficult and must be done by chemical analysis. Through the 
courtesy of the Chief of the Bureau of Chemistry exact data can be 
presented on this point from analyses by Mr. Lorin H. Bailey. In 
samples of dormant blueberry wood, taken in early spring when 
growth was about to begin, the ratio of sugar to starch proved to be 
seven times what it was in similar dormant wood taken in autumn. 
I desire at this time to comment on the fact that one of my 
colleagues reading the manuscript outline of this address criticized 
the use of the word "stimulate" as applied to the effect which 
chilling produces on these dormant plants. His idea was that the 
chilling induced certain physiological changes in the cell contents, 
but that the actual stimulation to growth came from the temperatures 
that followed the chilling. I defend, however, the propriety of the 
language I have used, for although the later stages of growth ad- 
mittedly can not take place without warm temperatures, not only 
does the transformation from starch to sugar take place at the 
chilling temperature, but the buds actually swell and push if the 
chilling temperature is continued for several months. In illustra- 
tion I may cite the following experiments : 
On March 3, 1915, 286 cuttings were made from dormant outdoor 
blueberry plants. They were stored in bundles, some in moist sphag- 
num moss, others in moist birch sawdust, at a contemplated tempera- 
ture of 31° F., just below freezing. The cuttings remained in cold 
storage until December 6, a little more than nine months. An 
examination of the cuttings on that date showed that with the ex- 
ception of a small number which were mildewed and dead one or 
more buds had begim to swell on every cutting. In other words, 
