13 
VEGETABLE ABSORPTION. 
At the period when we hope to meet our readers at the commencement of another 
volume, Nature will have resumed activity, for the winter will have passed away. Out- 
ward appearances may be more or less strikingly different ; the garden may be rich 
with verdure and bloom, or it may be covered with snow, and be bound with ice ; 
still, with the undeniable increments of solar power, it must be influenced in a 
greater or less degree by the vivifying principle of light, which, in its passage through 
the organism to the earth, stimulates the roots, and induces what is termed the 
absorption of the sap. It is this absorption which claims our first attention. 
In all cases where theoretic hypotheses supply the place of discovered truth, it 
becomes a duty to cite those opinions which prevail at the existing period, referring 
faithfully to the authority whence they are derived. On the present occasion we 
shall confine ourselves chiefly to those portions of a lecture by Dr. Ph. B. Ayres, 
on " Absorption of Nutritious Matter," that have been given in page 93 of the 
" Pharmaceutical Times," Nov. 6th, 1847. 
" The food of plants always enters them in a liquid state, or dissolved in water. 
The spongy tissue of the extremities of the roots, or, as it is termed, the Spongioles, 
is so fine as not to permit any, even the most minute particles of solid matter, to 
pass through them." This opinion is conformable to the principle adopted by 
Dr. Lindley, and thus stated at paragraph 78 of his " Elements of Botany : " 
" Absorption takes place almost exclusively by the extremities called Spongelets, 
or Spongioles, which consist of a lax coating of cellular tissue lying upon a concentric 
layer of Ducts (transparent tubes, the sides of which are marked with rings, bars, 
or transverse streaks). Spongioles are not, however, a distinct organ, but are merely 
the young extremities of the roots." 
The reader will mark this last particular, as it will be found elucidatory of some 
critical observations which truth will claim during our investigation of the hypotheses 
of absorption. 
" The liquid derived from the soil is not absorbed by the whole surface of the 
roots, but only by their minute and spongy extremities ; and hence it is of great 
importance to preserve these when transplanting, because if they are destroyed the 
roots cease to absorb, and the plant dies." 
We must receive this opinion with much qualification, for it admits of many 
exceptions. The Spongioles are, in fact, tender developments at the extremities of 
the growing rootlets, and therefore may, in all probability, be referred to the recently 
produced or growing shoots. Many of our best phytologysts in former years — the 
late Dr. Aikin in particular — strongly advocated the opinion, that not a single bud, 
or even leaf, was developed without a corresponding downward process, which con- 
nected it with the earth. The doctrine might be carried too far in actual extent, 
