Botany. 453 
mordial utricle, or nitrogenous membrane, developed over its surface ; 
and then the cell-membrane (of cellulose) is deposited upon this. In 
Cryptogamous plants, such masses, of larger or smaller size, may be- 
come coated with a cell-membrane witliout any proper nucleus appear- 
ing. (p. 57-60.) Thus much for what relates to the anatomical condi- 
tion of the cell. 
Under the second head, the Physiological Condition of the Cell, our 
author treats first, of the cell as an organ of nutrition, next, as an or- 
gan of propagation, and finally, as an organ of motion. He pronoun- 
ces against the Knightian doctrine, that plants ultimately degenerate 
parenchymatous tissue of the root, ascends through the woody tissue, 
and that the assimilated sap returns through the bark, and thence more 
or less into the wood by means of the medullary rays, is very neatly 
Shown. “A few simple experiments leave no doubt about this. * * 
If the bark of a plant, best of a tree, is cut through in a ring down to 
above the wound; but if the wood is cut through, the greatest care be- 
ing taken to avoid injuring the bark, that portion of the plant above the 
he wood of the stem and branches 
by the powerful ex- 
Ing it fit to be applied to the nutrition of the plant. To this end the 
sap flows backwards from the leaves through the bark to the lower 
If the bark is cut off the 
stem in a ring, the growth of the portion below the wound stands as it 
are produced, é&c. ; roan 
'S Increased beyond the usual measure, thicker layers of wood are de- 
Posited, more fruit is perfected, this ripens sooner, &c. The deposition 
of starch which occurs in the cells of the medullary rays in autumn, 
