BULLETIN OF THE BUSSEY INSTITUTION. 125 
seasons when the grass has been burned off, or is otherwise scarce, 
the Indian ponies sometimes resort to the small twigs and bark 
of the cottonwood to sustain life. In extreme cases their owners 
have sometimes been driven to the same shift.” 
In the hope of throwing more light on the apparent superiority 
of the bark of conifers, I have tested several kinds of barks 
chemically for mannan in the same way that the woods of various 
trees, roots, and fruits have been examined, in former years, in 
this laboratory,* the idea being to ascertain how large a propor- 
tion of mannan is contained in the barks as compared with the 
quantities contained in the woods proper. 
At Durham, New Brunswick, during the summer of 1905, I 
availed myself of an excellent opportunity to collect several 
samples of inner bark of the fir (Picea balsamifera), pine ( Pinus 
strobus), spruce (Picea nigra), and larch (Larix Americana), 
as well as of the gray birch (Betula populifolia) and poplar 
(Populus tremuloides). 
In the case of the conifers, young, vigorous trees were selected. 
They were from 2 to 44 inches in diameter at the butt. The 
bark from the trunk wood, and in one instance from the larger 
limbs, was collected. The outer bark was first removed; the 
inner bark was then carefully peeled from the wood in as large 
pieces as possible. ‘These pieces were air dried in a warm room, 
and kept in a dry condition until the time of using. 
The sample of poplar bark was collected in the same manner. 
The tree measured 34 inches in diameter at the lower end. Bark 
from the trunk wood only was taken. 
In case of the birch one limb, about 24 inches in diameter, of a 
forked tree, was selected. The rather thick, greenish inner bark 
was taken as the sample. 
In preparing each sample for use the material was cut into 
small pieces and ground to a fine meal in a hand-mill. 
The method of procedure was similar to that followed pre- 
viously.t A quantity of the powdered material equal to about 
twenty grams of the substance reckoned as dry at 100°C. was 
boiled in a flask, with a reflux condenser, for three hours, with 
* Bulletin of the Bussey Institution, 1903, 3. 47. 
+ Bussey Bulletin, 1903, 3. 47. 
