VOL. LXIir.] PHILOSOPHICAL TRANSACTIONS. 403 



alone did not in the least partake of the common state of numbness and sufFering, 

 but was on the contrary in full vegetation. The sap in it must have been ex- 

 tremely rarefied, and in very quick motion, while that of the tree was (jreatly 

 condensed, and in total inaction. How is it possible to conceive a circulation 

 of the sap from such a frozen root and stock, to a branch full of vigour, and 

 loaded with leaves and flowers? Surely this experiment must appear conclusive 

 against the system of circulation ; since in this case it could at best only be 

 admitted to have taken place in the vegetating branch ; and that would very 

 improperly be termed circulation, which should be confined to one limb. 



2. This experiment proves, that each part of a tree is furnished with a sufficient 

 quantity of sap to effect the first production of buds, flowers, and fruits. There 

 is little probability that the branch drawn into the hot-house should have derived 

 its sap from the roots of the tree: as they, at that time, lay in a very small 

 quantity of earth, rendered extremely hard and dry by the frost, they could have 

 but little fluid to spare; and even this, considering the congealed state of the 

 lymphatic vessels of the stock, could have found no passage to the branch. 

 This branch must of course have been enabled to continue its vegetation by the 

 quantity of sap with which it was provided, the consumption of which must 

 have been supplied at the first breaking of the frost. This truth, now demon- 

 strable by experience, had been pointed out before by a multiplicity of other 

 facts. Every body may have observed that a tree, which has been blown down 

 in autumn, though separated from its trunk, begins the same vegetation, that it 

 would have done if it had remained standing. Its buds open, it bears leaves, and 

 even shoots, which sometimes are very long, and must be the effects of the sap 

 it contained. It is true indeed that this appearance does not continue long, 

 because the provision of sap once exhausted, without being renewed, every thing 

 must of necessity perish. An effect of the like kind often deceives us in trees that 

 have been newly planted, and in scions, which produce flowers and even fruits, 

 without ever having taken root. But in this case, the symptoms which would 

 seem to promise life, are on the contrary the forerunners of death; because the 

 leaves, being from their nature the most powerful organs of transpiration and 

 dissipation, the graft is the more readily exhausted, when there is no root to 

 furnish it with a fresh supply of nutritive juices. 



3. This experiment proves that it is heat which unfolds the leaves, and pro- 

 duces the other parts of fructification, in the branch exposed to its .notion. 

 Autumn is the time in which nature employs itself, as it were cljindestinely, 

 under the cover of the leaves, in forming the buds, which contain the 

 rudiments of the leaves, blossoms, and fruits, that are to be produced in 

 the course of the succeeding summer. These buds prepare and work themselves 

 out, during the winter, under the rough coats that are destined to preserve them 



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