T H E M A C i A Z i N E 
OF 
TRG m?)00l OF AGKIOULTURG, 
COLOMBO. 
Added as Supplement monthly to the ^^TllOPICAL AOIUOULTmiSTr 
Tlie following pages include the 
AfjriruUut'c for Septeml>er : — 
1‘liANTS AND WATEK. 
liANTS may, in a general way, be 
said to be composed of water and 
solid materitil. The amount of 
water in plants is very variable — 
ripe seed containing about l.'i per 
cent; stems and leaves of ordinary herbaceous 
plants, on an average, 70 per cent ; many water 
plants as welt as some fruits and roots, 00 per 
cent : fungi up to Oo per cent. 
According to Niegeli's theory every molecule or 
ultimate soli<l particle of the plant is sur- 
rounded by a film or sheath of water; when the 
molecules are largo, the proportiou of water is 
small, while when tho molecules are small, t he pro- 
portion of water is large. The quantity of water, 
accordiug to this theory, varies only within certain 
limits. If it be present beyond these limits, i.e., if 
thero be too much or too little water, the texture of 
the plant will be destroyed. Loss of water causes 
O' contraction, gain or absorption of water an 
increase or swelling of the plant body. Tho pro- 
Portiou of water in a plant dopends partly on the 
aeason of tho year ; and when growth i.s going on 
'igorously there, is always an increase' of water. 
Nearly all the water in plants is taken in by 
• he root, s, though, according to tVarriugtfiU, when 
ram occurs after .severe drought, water may he 
taken up to some e.xtent through the loaves. 
Apart from tho necessity for water in tho plant 
o meet tho evaporation which goes on through 
the leaves, and thus prevent what is popularly 
spokeu of as the drooping of the plant, water is 
contents of the Maefazine of the School of 
ver>’ necessary as a mislium by which plant food 
in the soil enters the plant. All the plant food 
which is derived from live soil is taken in as.soUi- 
tious by the process (d osmose. It is a common 
fallacy that plant food is also taken into the plant 
ns solid mutter. The solutions which are taken in 
by the roots are either of substances found ready 
ilissolvtsl,orofsulistances whitdi havebeen dissolved 
through the action of the acid sap in tho mots. A 
tolerably large aiuount of water is rtniuired to dis- 
solve nud carry a small nmotuit of plant fooil from 
the soil into the plant, as tho solutions whi<'.li enter 
are very weak ones. Uwingfotlierapklevaporatimi 
of water throtigh tho leaves, these weak 
solutions are concmitrated in the tipper part* of 
the plant, and the required ingrtslieute nri' appro- 
priated by the plant for file formation of new 
I i.ssue, while those not required are got rid of ns 
iuenisUtions ou the older tissues. 
A little time ago we liuard artesian wells 
objected to on the ground that the Water they 
sujiplied was iwuctically piu-e water, that is water 
’Without silt (so it was put tons) ; it being maizi- 
tained that the water of artesian wells was 
perfectly useless for cultiv ntion juii-poses. Now' 
water available by a plant may have silt in sus- 
ix^usion. plant food in solution, or neither, Imt 
only certain substances which Imlp water to 
act upon iusoluble plant foodin the soil and render 
it soluble. While irrigation water tas irri- 
gation is carried out in Ceylon) carries silt in 
suspension, it is not to Ih‘ supposctl that it is of 
value solely as a carrier of silt, for hesidas cniiy- 
ing siibetnnces in mechanical siiapeiision, it 
would also hold substaucos in Mdiitioii, as well as 
act as the medium for conveying soluble plant 
fixxi how’uver derived, into the plant. To say 
that the sui>plying of water, without plant food 
in suspension orsolution, to a plant is of no value 
to it, is to depn^cate all "dry cultivation " to 
say that rain is a superdnity in agriculture, 'that 
watering by tho baud in lIorticultHre is a waste 
of labour. 
Let it however he remembered that water in 
1 addition to being a carrier of silt may coutaiu up 
