NOTES AND ABSTRACTS. 



837 



was established among the Indians prior to 1673. The early Vermont 

 settlers learned the art from them, and depended almost entirely on the 

 Maple for their domestic sugar supply. Maple goods are now, however, 

 used as a delicacy, and command a relatively high price. Neither the 

 sugar-making nor the tree from which the sweet sap flows has hitherto 

 received close scientific study. But little is found in American literature, 

 and practically nothing in European, while there are many obscure points 

 in connection with the sap flow which seemed worth clearing up. 

 Accordingly, in the winter of 1896-7, the Vermont Agricultural Station 

 planned a study of the general problem. 



The Maple trunk consists of a reddish-brown heartwood and yellowish- 

 white sapwood. The sapwood is thicker than in many trees, averaging 

 6} inches. It contains the living cells, whereas the heartwood is lifeless 

 and functionless. It consists of clcsed cells and vessels packed closely 

 together, within which are held water, food substances, and gas. 



The water enters the tree by its roots, and, unless the tree is wounded, 

 its only avenue of escape is via the leaves. Its main service is as a tissue- 

 builder and as a carrier of food, and it may comprise from 25-60 per cent, 

 of the weight of the tree. It ascends the tree from the woody stem ; how 

 it does this is not clearly understood. Root pressure is perhaps the cause 

 of the ascent in some species, but does not appear to be an important 

 factor in the case of the Maple. 



The starch is manufactured in the leaves under the influence of 

 sunlight, and is later transformed into sugar, and the sugar-content of the 

 sap depends upon the conditions of the preceding season as to sunlight, 

 leaf development, and consequent starch storage. This has been 

 proved in recent years, when the defoliation of the trees by the forest 

 caterpillars was followed by seasons in which the sap carried much less 

 sugar than usual. The relation of foliage development to sugar-content is 

 a very close one. The variation in amount of sunshine at different periods 

 during the preceding summer also influences the quality of the sap. The 

 excess of these sugar-making foods gathered beyond immediate needs 

 during the summer months is stored for use in the early growth of the 

 following spring. This storage occurs chiefly in certain wood-cells, the 

 starch being deposited in the outer cells first, and progressively inwards. 

 In the spring this reserve food is drawn upon as sugar in the same order, 

 disappearing from the outer cells first, and progressively inwards, 

 Coincidently with the disappearance of the starch in the latter part of 

 the winter, micro-chemical tests of the tissues have shown an increase in 

 the amounts of the soluble carbohydrates, cane sugar, dextrin, and glucose. 

 When a branch was cut in mid-winter and kept for some time in a warm 

 room, these same changes were observed. It is safe to observe that in the 

 Maple, as in other plants, these transformations are due to and controlled 

 by the activities of the protoplasm, and that they are directly brought 

 about by chemical ferments or enzymes, secreted by the living cells in 

 which the starch is stored or by other cells closely adjacent to them. 

 Maple sap averages over 3 per cent, of sugar, and also contains other con- 

 stituents. 



A "good sap day," or "a good run of sap," occurs only after the air 

 temperature has remained below freezing for some time. If following 



