170 NATURAL HISTORY UF THE FARM 



ion made tlirough the Ixirk, from every wound or 

 broken twig, the sap flows copiously. It flows first on 

 the sor.lh side of the tree, where the sun shines, and it 

 flows most cojiiously during the warmer part of the day. 

 It ceases at night when the treetop is cooled and the 

 pressure equalized. It slackens on cloud}' da>'s, and 

 ceases altogether wlien the ground gets warmer. The 1< )Tiger 

 the period of alternating bright sunshiny da\-s and sharp 

 frosty nights, the greater the amount of sap obtainable. 

 Tiie greater, also, is the drain of the food reser\'e of the 

 tree : but the provident maples store more than they need, 

 and they are not injured by the loss of such aj.ounts as may 

 be obtained by proper tapping. They often ha\'e to meet such 

 losses tlirough natural causes — such as the tappings of the sap- 

 suckers, and the "bleeding" from the stubs of broken boughs. 

 Other deciduous woody plants lose their sap in similar 

 ways. Every vine-grower knows that grape vines, trbnmed 

 at the time of abundant sap-flow, "bleed" profusely from the 

 base of ever>^ branch removed — so profusely, indeed, that the 

 plant may be wealvcned by such inopportune treatment. Ash 

 and elm and beech and butternut and other deciduous trees 

 will yield sap in its season, but only a few of the maples >deld 

 a sap tliat is sufhcient in quantity, rich enough in sugar, and 

 sufliciently well flavored to be important to us. The sugar 

 maple is the best maple, both in yield and in quality of 

 product: a variety of it known as the black maple, is 

 especially esteemed by many growers. Red and silver 

 maples yield a copious, but more watery sap. The Oregon 

 maple is a western species from which a little sugar is made. 

 The yield of the lesser maples and of the related box-elders is 

 of no consequence. Most tree-saps, on evaporation, will 

 yield some sort of a sweetish treacle; but only the maples 

 yield palatable syrups and sugars, whose fla\'or is improved 

 by the non-sugar>' natural substances present in the sap. 



