Page:Philosophical Transactions - Volume 095.djvu/116

102 iosl Mr. Knight concerning the State in xiuhich

sweetness in decoctions of the sycamoire wood in winter. I am therefore inclined to believe that the saccharine matter existing in the ascending sap is not immediately, or wholly, derived from the fliiid which had circulated through the leaf in the preceding year ; but that it is generated by a process similar to that of the germination of seeds, and tiiat the same process is always going forward during the spring and summer, as long as the tree continues to generate new corgans. But towards the. conclusion of the summer I conceive that the true sap simply accumulates in the alburnum, and thus adds to the spedfic gravity of winter*felled wood^ and increases the quantity of its extractive matter.

I have some reasons to beUeve that the true sap descends through the alburnum as well as through the bark, and I have been informed that if the bark be taken from the trunks of trees in the spring, and such trees be suffered to grow till the fol- lowing winter^ the alburnum acquires a great degree of hardness and durability. If subsequent experiments prove that the true sap descends through the alburnum, it will be easy to point out the cause why trees continue to vegetate after all communication between the leaves and roots, through the bark, has been intercepted : and why some portion of alburnous matter is in all trees^ generated below indsions through the bark.

It was my intention this year to have troubled you widi some observatioiis on the reproduction of the buds and roots of trees ;

exception. I spoke on the authority of numerous experiments ; hut they had been made late in the summer ; and on repeating the same experiments at an earlier period, 1 found the result »n conformity with my experiments on other trees.
 * I have in a former paper stated that the perpendicular shoots of the vine form an