TH E iVI AG A.Z 1 N K 
OF 
COLOMBO. 
Arlded as Supplement monthh/ to the TROPICAL AGRICULTURIST:' 
The following pages include the 
AgricuUwe for September : — 
PLANTS AND WATER. 
contents of the Magazine of the School of 
LANTS may, in a general way, be 
said to be composed of water and 
solid material. The amount of 
water in plants is very variable- 
ripe seed containing about 13 per 
cent; stems^'and leaves of ordinary^ herbaceous 
plants, on an average, 70 per cent ; many water 
plants as well as some fruits and roots, 90 per 
cent ; f utigi Hp to 95 per cent. 
According to'Nregeli's theory every molecule or 
ultimate solid particle of the plant is sur- 
rounded by a film or sheath of water ; when the 
molecules are large, the proportion of water is 
small, while when the molecules are small, the pro- 
portion of water is large. The quantity of water, 
according to this theory, varies only within certain 
limits. If it be present beyond these limits; i.e., if 
there be too much or too little water, the texture of 
the plant will be destroyed. Loss of water causes 
>a contraction, gain or absorption of water an 
increase or swelling of the plant body. The pro- 
portion of water in a plant depends partly on the 
reason of the year ; and when growth is going on 
vigorously there is always an increase of water. 
Nearly all the water in plants is taken in by 
tlie roots, though, according to Warrington, when 
rain occurs after severe drought, water may be 
taken lip to some extent through the leaves. 
Apart from the necessity for water in the plant 
to meet the px iiporation which goes on through 
the loaves, and thus prevent what is pn])iiliirly 
epokeu of as the drooping of the phuit, wuteris 
very necessary as a medium by which plant food 
in the soil enters the plant. All the plant food 
wliich is derived from the soil is taken in as solu- 
tions by the process of osmose. It is a common 
fallacy that plant food is also taken into the plant 
as solid matter. The solutions which are taken in 
by the roots are either of substances found ready 
dissolved, or of substances which have been dissolved 
through the action of the acid sap in the roots. A 
tolerably large amount of water is required to dis- 
solve and carry a small amount of plant food fi'om 
the soil into the plant, as the solutions which enter 
are very weak ones. Owingto the rapid evaporation 
of water through the leaves, these weak 
solutions are concentrated in the upper parts of 
the plant, and the required ingredients are apjno- 
priated by the plant for the formation of new 
tissue, while those not required are got rid of as 
incrustations on the older tissues. 
A little time ago Ave heard artesian Avells 
objected to on the ground that the water they 
supj)lied was practically pure water, that is water 
without silt (so it was xnit to us) ; it being main- 
tained that the water of artesian wells was 
perfectly useless for cultivation purposes. Now 
water available by a plant may have silt in sus- 
pension, plant food in solution, or neither, but 
only certain substances which help water to 
act upon insoluble plant food in the soil and render 
it soluble. While irrigation water (as irri- 
gation is carried out in Ceylon) carries silt in 
suspension, it is not to be supposed that it is of 
value solely as a cari'ier of silt, for besides carry- 
ing substances in mechanical su.spensioii, it 
would also hold substances insolation, as well as 
act as the medium for conveying soluble plant 
food, however derived, into the plant. To say 
that the supplying of water, without plant food 
in suspension or solution, to a plant is of no value 
to it, is to deprecate all " tlry cultivation," to 
say that rain is a superrtuity in agriculture, tliat 
watering by the hand in Horticulture is a waste 
of biltour. 
Ji(,'t it Iiowcver be remembered that wntiT in 
addition to heiiig ft carrier of silt may coutaiu up 
