448 VEGETABLE RESPIRATION. NoTzr XXXVII.

the propulſive power of theie abſorbents of the roots of it. Veget. Stat. p- 102. Such a power cannot be produced by capillary attradtion, as that could only raiſe a Aud nearly to the upper edge of the attracting cylinder, but not enable it to flow over that edge, and much lefs to riſe 21 feet above it. What then can this power be owing to? Doubtleſs to the living activity of the abſorbent veſſels, and to their increaſed vivacity from the influence of the warmth of the ſpring ſucceeding the winter's cold, and their thence greater ſuſceptibility to irritation from the juices which they abſorb, reſembling in all circum ſtances the ation of the living veſſels of animals.

NOTE XXXVI. VEGETABLE RESPIRATION.

While ſpread in air the leaves reſpirimg play. EZINTO INE 4.34:

I. THEREz have been various opinions concerning the uſe of the leaves of plants in the vegetable ceconomy. Some have contended that they are perſpiratory organs; this does not ſeem probable from an experiment of Dr. Hales, Veg. Stat. p. 30. He found by cutting oft branches of trees with apples on them, and taking off the leaves, that an apple exhaled about as much as two leaves, the ſurfaces of which were nearly equal to the apple z whence it would appear that apples have as good a claim