May, 1914.] Starch Reserve in Birch and Maple. 
3i7 
STARCH RESERVE IN RELATION TO THE PRODUCTION 
OF SUGAR, FLOWERS, LEAVES, AND SEED IN 
BIRCH AND MAPLE. 
Forest B. H. Brown. 
American scientific literature is lacking in a standard treatment 
of subjects dealing with the stored reserve in our fruit and forest 
trees, such as have been made by Busgen in his “ Waldbaume,” 
and in other still more recent German publications. The work of 
Jones and others of Vermont (Bull. 103, 1903) contains much 
information on the maples. But this work does not furnish the 
drawings essential to a clear presentation of starch storage, 
and the description is inadequate. Even in this bulletin, no at¬ 
tempt is made to show in what way the vast amount of potential 
energy represented in the stored starch is used, otherwise than in 
the production of sugar, while the authors themselves conclude 
that rarely is there used, in this way, more than 4% of the total 
starch stored in a tree. 
This fact, together with the very conflicting statements made 
in the available published records, has led the writer to publish 
these few preliminary studies. The ease with which such studies 
may be carried on, together with their direct bearing upon many 
of the vital problems of forestry and various branches of agricul¬ 
ture, would suggest their general fitness to be included in the bot¬ 
any laboratory course, even in the high school possessed of only 
one microscope. 
Data for the present paper were taken from selected trees of 
birch and maple growing on the Ohio State University campus. 
Particular attention was given to a sugar maple, Acer saccharum 
Marsh., north-west of the law building. From a 1-year twing of 
this tree, a cross-section 20 mic. in thickness was cut April 1, by 
means of a sliding microtome, stained one minute in iodine, and 
then mounted in glycerine. A camera drawing was made, Fig. 1, 
the magnification being shown by the accompanying scale. Simi¬ 
larly, a section was cut from a root S mm. in diameter, Fig. 2. 
The granules of starch have been indicated in solid black. In the 
stem the starch grains are shown in the medullary rays (u. m. and 
b. m.), wood parenchyma (w. p.), and in all the primary xylem 
tissues except the vessels. The wood fibres were empty in all the 
sections studied; but in the root, the wood fibres, as well as the 
wood parenchyma and medullary rays, are filled. Also, many of 
the tissues of the bark, both of stem and root, contain starch. 
Beginning with the first layer inside the cork, they are, in order, 
as follows: the periderm, collenchyma, thin walled parenchyma, 
bast parenchyma, and bast rays. The maple, however, con¬ 
tained less starch at this period in the bark tissues than the birch 
