PER CENT. OF SAP. 229 



of the woody fibre for water. Is not this, then, the proper 

 name for the force which curries up the crude sap ? 



The wood of growing trees when cut from near the sur- 

 face, though apparently dry, contains nearly fifty per cent, 

 of water; and in the young twigs,. with a living pith, the 

 proportion is even greater. A number of analyses have been 

 made of specimens collected at different seasons during the 

 past year, of which a tabular statement is appended. 



There is good reason to believe that the sap in ordinary 

 trees begins to move first in the buds, and that the first sup- 

 ply of water exhaled in the spring is derived from the sap- 

 wood. Branches of aspen and red maple, two feet in length, 

 were cut on the twenty-sixth of March and placed in a warm 

 room in an empty vase. The flower-buds developed without 

 any other water than what they could abstract from the 

 wood, so that on the fifth day the staminate catkins of the 

 aspen were four inches long, and the pollen well developed. 

 It is by no means uncommon to see large branches, which 

 have been removed from apple trees early in the spring, covered 

 with blossoms in a similar way while lying on the ground. 



It is a Well-established fact that the roots of most woody 

 plants have not power at any season to force w r ater to any 

 considerable height when separated from their stems. Upon 

 this point a large number of observations have been made, 

 which will be described in another place. 



The roots of all plants growing on ordinary soil develop 

 most freely and absorb mosUibundantly when the earth is well 

 drained and aerated. Thus Ave find that the crude sap im- 

 bibed by the root-hairs from the surface of the particles of the 

 soil seems to be taken up in a dry state, that is, it appears to 

 be absorbed molecule by molecule, no fluid water being visible, 

 and carried in this form through all the cellulose membranes 

 between the earth and the leaf, by which it is to be digested 

 or exhaled. We do not say this is literally true, but it ac- 

 cords very nearly with what is constantly to be seen in some 

 species of plants. The circulation of the sap in a poplar tree 

 is very dry compared with that of the blood of any animal. 

 Not a drop of moisture will ever flow from the wood of an 

 aspen, so far as we have observed. Nevertheless, it grows 

 very freely and starts very early in the season. 



