169 
SAP OF SUGAR MAPLE. 
Flow of Sap. 
Tlie amount of sap which can be withdrawn from living 
trees furnishes, not indeed a measure of the quantity of water 
sucked up by their roots from the ground—for we cannot 
extract from a tree its whole moisture—hut numerical data 
which may aid the imagination to form a general notion of the 
powerful action of the forest as an absorbent of humidity from 
the earth. 
The only forest tree known to Europe and North America, 
the sap of which is largely enough applied to economical uses 
to have made the amount of its flow a matter of practical 
importance and popular observation, is the sugar maple, Acer 
saccharinum , of the Anglo-American Provinces and States. 
In the course of a single “ sugar season,” which lasts ordinarily 
from twenty-five to thirty days, a sugar maple two feet in 
diameter will yield not less than twenty gallons of sap, and 
sometimes much more.* This, however, is hut a trifling pro- 
growth of trees, the ground is generally too thickly covered with leaves 
to allow much room for ground mosses. In the more open woods of 
Europe, this form of vegetation is more frequent—as, indeed, are many 
other small plants of a more inviting character—than in the native Ameri¬ 
can forest. See, on the cryptogams and wood plants, Rossmasslek, Dev 
Wald , pp. 33 et seqq. 
* Emerson (Trees of Massachusetts , p. 493) mentions a maple six feet 
in diameter, as having yielded a barrel, or thirty-one and a half gallons 
of sap in twenty-four hours, and another, the dimensions of which are not 
stated, as having yielded one hundred and seventy-five gallons in the course 
of the season. The Cultivator , an American agricultural journal, for June, 
1842, states that twenty gallons of sap were drawn in eighteen hours from 
a single maple, two and a half feet in diameter, in the town of Warner, 
New Hampshire, and the truth of this account has been verified by per¬ 
sonal inquiry made in my behalf. This tree was of the original forest 
growth, and had been left standing when the ground around it was cleared. 
It was tapped only every other year, and then with six or eight incisions. 
Dr. Williams (.History of Vermont , i, p. 91) says: “A man much em¬ 
ployedinmaking maple sugar, found that, for twenty-one days together, 
a maple tree discharged seven and a half gallons per day.” 
An intelligent correspondent, of much experience in the manufacture 
