May 24 , 1894. 
JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
409 
way can moisture be rendered capable of sustaining cut flowers 
or foliage in a condition of freshness for a long period. The case 
may not of course apply to roots. But then, how is the case with 
regard to plants in pots ? Here we find the stronger and more 
absorbent roots always at the bottom of the pots, where moisture 
is usually most plentiful. It is here certainly not a case of vapour 
rising from below, as that is in pot-plant roots quite out of the 
question, for they thrive only when moisture is in absolute contact. 
The fact that some weeds have been found to exist in dry gravel 
during hot weather simply shows that there is in the gravel all the 
same some moisture not visible to our senses, but enough to keep 
the plants alive, though not thriving. It is an understood axiom 
that stone or rock always contains moisture, which serves to 
fertilise soil, and keep plants in existence. We see that fact 
on the plants are almost instantaneous ? Naturally the inference 
is that they have in liquid form been absorbed by the roots. Now, 
if we adopt the vapour theory of feeding roots by ascending 
moisture in the soil we should have to admit that our practice of 
top-dressing soil for the purpose of keeping roots near the surface 
where they can be directly fed by moisture and manure would be 
no longer tenable. Practically it is most successful, and where 
practised is a long way more useful than are scientific aiguments. 
Why are the young roots termed spongioles but that their sponge¬ 
like formation indicates capacity to absorb liquids ? 
Let anyone take a plant in a pot having an open or porous 
base, stand it over a tank from which vapour is, because of the 
temperature of the water in it, constantly rising; but give the 
plant no water from the surface ; and then see which after all 
Fig. 66.—an AMATEUK ORCHID GROWER’S DREAM. 
illustrated in old stone or even brick walls, which will, although 
apparently baked dry, yet sustain certain descriptions of vegetable 
life. 
Possibly the theory put forth originated from the undoubted 
fact that parasitical and epiphytal plants do chiefly exist through 
their roots, on vapour or aerial moisture. These, however, con¬ 
stitute very diverse genera from plants that must of necessity root 
in the soil, and still more so from aquatic and semi-aquatic plants 
whose roots exist almost only in water. If in this latter case water 
is actually absorbed by the roots, although when so absorbed 
changed into sap, why may we not suppose that water is equally, 
though, of course, in a lesser degree, absorbed by the roots of plants 
that grow in the soil ? It is urged that water when applied to 
soil, and manure in it, changes the solid material of the latter into 
something that is volatile and absorbent, practically into vapour, 
and in that way roots are fed ; but if the contact of water with 
manures changes their solids into liquids, in fact renders them 
soluble, may not that alone suffice for the fertilisation of roots 
without suggesting the vaporous theory ? 
When we place solid manures in water and thus practically 
liquify them or convert them into a liquid form, and apply them to 
plants in that way from the surface, do we not find that their effects 
thrives best—that one, or one entirely similar standing in perhaps 
a dry arid house, on a dry stage, and in an ordinary close pit, yet 
is regularly watered from above. The experiment may leave 
something to be desired, but at least it would afford the best means 
we have of testing the truth or otherwise of the said botanist’s 
vapour theory.—A. D. _ 
I FIND that in my letter of last week (page 388) I was wrong 
in my facts or statements. I now gather, with apologies, that (1) 
the root hairs of plants are supposed to have the power by 
mechanical decomposition of getting at that vaporous form of 
liquid which alone they can assimilate ; and (2) that moisture 
while risirg through the soil is not necessarily, at all events, in that 
vaporous form more than any other liquid. But this does not in¬ 
validate what I wanted to prove—that moisture does continually 
rise through the soil, and can carry upwards with its manurial 
elements.—W. R. Raillem. 
Ip Mr. W. R. Raillem desires to know whether plants will take 
up water in a liquid form let him cut a few growths from one of 
his Rose bushes, lay them in the sun for a little while till the leaves 
