REPOIITS OF LOCAL yOClETlES. 341 



By Thee disposed into ootigenhil soils, 

 Stands e:ich attractive plant, and sucks and swells 

 The juicy tide; a twiniiij^ mass of tubes. 

 At Tliy t'ouiniaiiil tiie vernal sun awakes 

 The torpid saj), detruded to tlie root 

 ]{y wintry winds; that now, in lluent dance, 

 And lively fermentation mountin<^, spreads 

 , All this innumerous-color'd scene of things." 



So sang one of nature's truest poets. But when you ask lue to reveal the 

 liidden things of nature, I am reminded of the question put to one of old : 

 •'Who is this that darkeneth counsel by words without knowledge?" 



As we gaze at the oak, whose branches are tossed so defiantly to the storms 

 of wind and rain, and whose sides are so deeply furrowed by age, the question 

 naturally arises, what agencies have been at work, to transform the tiny germ, 

 so carefully hidden within the acorn, into this mighty monarch of the forest. 



The popular idea that the sap ascends the tree, in the spring, and remains 

 somewhere until fall, and then descends again, seems after all to be only partly 

 erroneous. 



It is true that the sap ascends in the spring, and it is also true, that it does 

 so at all other times, when the ground is warm enough for the roots to extract 

 moisture therefrom. Stockhardt found by actual experiment, that the wood of 

 rt tree contains more sap in the months of December and January, than at any 

 other time of the year. This, upon reflection, seems reasonable. 



But in order that we may fully understand and intelligently follow the sa])in 

 its circulation, it will become necessary to look a little at the structure of the 

 plant or tree. 



The basis of all vegetable organization seems to be the cell. These cells are 

 minute closed sacks (being only from one one-hundreth, to one tliree-hundreths 

 of an inch in diameter), are filled with fluids and are therefore capable of 

 assuming a variety of shapes and positions by compression from within or 

 without. 



As the plant expands in growth, the cells, too, expand and divide and sub- 

 divide, thus making two or more perfect cells from one. Some of them con- 

 tain air, others are filled with starch, and whatever may be stored up for the 

 future use of the plant. Others become hardened by the deposition of various 

 matters, and thus woody fibre is formed. 



It is through the wood cells, too, that the sap passes on its way to the leaves. 

 The wood cells seem to contain air as well as water, and both air and water are 

 greatly affected by heat and cold, both are expanded by heat, and both con- 

 tracted by cold. 



Water is said to increase in volume one-twentieth of its own bulk on being 

 raised from the freezing to the boiling point, and air increases its bulk one- 

 third by the same change of temperature. The crude sap is composed largely 

 of water, which is absorbed by the roots and evaporated by the leaves. When 

 we take into consideration the fact that most of our forest trees lose their 

 foliage early in the autumn, before the ground is frozen sufficiently hard to 

 cause the roots to cease their labors, and that the roots renew, so to speak, their 

 pumping process, whenever there is a sufficient rise in the temperature, is it any 

 wonder that the whole body of the tree becomes gorged with sap? This sap, 

 according to Prof. Johnson, remains motionless until the leaves are sufficiently 

 expanded to perform their peculiar fuuctions, unless some external cause acts 



