346 
THE EDITOR’S REPLY, 
opinions as to two very material points in vegetable physics and economy. 
We assert that the sap is diffusible, hi all directions , throughout the 
system of the plant; but we deny that there is any regular circulation. 
The difference between diffusion and circulation we conceive to be 
this:—in the first, the sap pervades every part, like water absorbed 
and retained by a sponge ; the second supposes a constant flux and 
reflux, or continued ascent and descent in different sets of vessels, 
acting like the arteries and veins in the human body. 
This latter notion has been held by many phytologists ever since the 
time of Duhamel, but is now discarded, because there is no propulsive 
organ or organs in a plant to be compared with the action of the heart 
of animals. 
The next point, and which forms so prominent a part of our theory, 
is, our denial that the sap is “ organisable that is, we deny the possi¬ 
bility of the various membranes and organs of a plant being formed of 
or increased by any change of the sap. Our reasons for this denial are 
two:—first, no organised body, like a plant, can be formed of unorgan¬ 
ised matter, which the sap of plants undoubtedly is ; and, secondly, 
no organised body can originate itself, or acquire existence without a 
previously existing organised rudiment : and as no entire plant can 
originate itself, so neither can any single organ or member of a plant 
gain identical existence without a similar origin. 
When the doctrine of equivocal generation was entertained and 
believed, the apparent spontaneous production of weeds, of maggots, of 
reptiles, and of fishes, was easily accounted for;—they were supposed 
to be the offspring of corruption! A modification of this silly and 
groundless doctrine was easily applied to explain the unaccountable 
increase of the stems of trees and shrubs; even certain chemists, for 
w 7 ant of due consideration, believed, and perhaps still believe that, by 
the union of what they call “ the great powers of nature,” organised 
forms might be generated, and continue as additions to the animal or 
vegetable kingdoms for ever. The same idea leads some naturalists to 
suppose that creation has not yet ceased, as new species of both plants 
and animals are every day being discovered, which, they think, were 
not in existence before. Such notions belong to what is called tran¬ 
scendental philosophy, which gains but few converts. 
On the above two particulars, viz. the non-circulation and non-organ- 
isable property of the sap, the whole of our theory hinges ; and if they 
can be overturned by cogent reasoning and fair (we shall not say 
indubitable) proof, all our views on that portion of phytological 
knowledge must fall to the ground. 
We think it needless to play the preceptor in correcting some mis¬ 
apprehensions and misnomers in the concluding part of your comm uni- 
