PLANT INDUSTRIES 311 
maple sap and, as ordinarily used, it contains from 30 to 40 
per cent of the water originally in the sap.1 
The sugar-making season is short, because, as soon as new 
protoplasm is developed in great abundance, the sap no longer 
makes acceptable sugar. Maple trees may be used from year to 
year indefinitely without apparent injury due to the withdrawal 
of sap, but the stem may be weakened by too frequent boring 
at one level, and the wound, though it heals in one or two 
years, may serve as a place of entrance for disease organisms. 
Fic. 234. A Cuban sugar-cane field 
Standing cane is seen at the left, between the men and the trees: in the foreground 
the men are loading sap-laden stalks upon the carts. Note the heavy soil covering 
of leaves that have been stripped from the sugar-cane stalks 
Sugar-maple groves are being planted in some places for 
the sugar product, but other plants of more rapid growth and 
larger sugar production will doubtless prevent maple sugar 
from entering largely into sugar consumption. The distinctive 
flavor of maple sugar and sirup, however, will enable it to 
continue as a highly desired article of commerce. 
1‘*The Maple Sugar Industry,’’ Bulletin 59, Bureau of Forestry, U.S. 
Dept. Agr., 1905; '* Maple Sap Sirup,’’ Bulletin 134, Bureau of Chemistry, 
U.S. Dept. Agr., 1910; ‘' The Production of Maple Sirup and Sugar,’ Farm- 
ers’ Bulletin 516, U.S. Dept. Agr., 1912. 
