SECT. I. EXCITABILITY. 455 



vital energies altogether. But this opinion is evi- 

 dently founded on a mistake, as is proved by the 

 example of such plants as protrude their leaves and 

 flowers in the winter season only, such as many of 

 the Mosses ; as well as by the dissection of the yet 

 unfolded buds at different periods of the winter, 

 even in the case of such plants as protrude their 

 leaves and blossoms in the spring and summer, and 

 in which it has been already shown there is a regu- 

 lar, and gradual, and incipient developement of 

 parts, from the time of the bud's first appearance 

 till its ultimate opening in the spring. The sap, it 

 is true, flows much less freely, but is not wholly 

 stopped. Hales lopped off some branches from 

 plants of the Hazle, Vine, and Jessamine respect- 

 ively, in the course of the winter, and covered the 

 section of the separated branches with mastic, which 

 in a few days were found to have lost considerably 

 in weight ; whence he inferred the motion of the 

 sap, because it seems but reasonable to suppose that 

 the dissipation of sap thus lost would have been re- 

 paired if the branches had not been cut off. Du 

 Hamel planted some young trees in the autumn, 

 cutting off all the smaller fibres of the root, with a 

 view to watch the progress of the formation of new 

 ones. At the end of every fortnight he had the 

 plants taken up and examined with all possible care 

 to prevent injuring them, and found that, when it 

 did not actually freeze, new roots were always uni- 

 formly developed. 



