226 
Suppleidmt to tht Tropical AgncuHunsV* 
[September i, 1890. 
complete development takes place. Here then we 
see one important reason for the need of the 
plough and other tillage implement for breaking 
up and thoroughly aerating the soil. Other con- 
ditions being equally favourable then, the more 
thoroughly the soil is aerated the more freely 
will nitrification take place. The presence of 
moisture is another necessary condition, and 
hence during a period of extreme drought nitrifi- 
cation is at a standstill. On the other hand if 
the soil be unduly charged with water, nitrifi- 
cation is again reduced to a minimum, as in 
the case of heavy, badly-drained clays, and this 
for more than one reason. Proper aeration cannot 
go on in a soil of this nature ; while the pre- 
sence of a large amount of moisture in a soil 
tends to reduce its temperature, and the tem- 
perature of the soil is another very important 
consideration. The action of the germs totally cease 
at a temperature below 12° C., while it goes on 
best at blood heat, that is about 98° P., and ceases 
again if the temperature be raised to 55° C., the 
germs being totally destroyed at 90° C. They are 
not killed by frost in the winter time in tem- 
perate regions, but only remain inactive and re- 
vive when the temperature rises, their action to 
any appreciable extent commencing above freez- 
ing point. Of Course the presence of nitrogen in 
an organic or inorganic form is necessary, as 
also that of some salifiable base to combine with 
the nitric acid and form nitrates, the form in 
which plants take in their nitrogenous food. 
Thus we see the importance of preserving a pro- 
per mechanical condition in soils by ploughing, 
harrowing, draining and such operations as bring 
about this very necessary result; for, the elaboration 
not only of nitrogenous plant food by the agency 
of nitrifying germs, but also that of mineral 
food by oxidation is greatly dependent thereon. 
With regard to the theory — claimed severally by 
Hellriegel and McAlpine — that special organisms, 
to which the name of bacteriods has been given, 
are contained in the root tubercles of leguminous 
plants, whose function is to work up the nitrogen 
in the atmosphere into compounds and fix these 
in the soil. A great deal has been written of late ; 
and much as one is inclined to favour this plaus- 
ible theory when the peculiar feeding habits of 
this order of plants is considered, yet a good deal 
has yet to be proved before it canbe accepted as an 
agiicultural fact, and this is the view of Sir John 
Lawes in his latest deliverance on the subject in 
which he details his own experiments to test the 
theory. 
INDIGENOUS FOOD PRODUCTS. CUL- 
TIVATED AND WILD. 
By W. a. De Silva. 
Lcyuminosai. 
24. iJolichos Hijiorus, L. ; Sin. Eollu. 
This is a cultivated legume largely grown in 
the warmer parts of the island in chenas and 
other open ,si)aces, generally with other crops. 
'I'he leaves which are compound and somewhat 
largo are green in colour and are hairy. The 
legumes are small and fiat, and contain from 3 
to 0 seed.s. The seeds when ripe have a reddish 
polished appearance, and they are flat. In culti- 
vation the crop is gathered three months after 
sowing. This legume is considered to be good 
cattle-food, the seed being boiled and given to 
stock for fattening. The stalks and leaves of 
the plant, when preserved, also form good and 
nourishing food for cattle. 
As a food product this grain is not much used, 
except in some localities where it is boiled, 
and eaten. 
25. Cassia Fistula, L. ; Sin. Ehela. 
This is a tree growing abundantly in the warmer 
parts of the Island, and is especially abundant in 
the dry districts, of the South-east and North- 
west. The trees attain to a good height, the 
leaves are compound (pinnate), and the leaflets 
which are green and entire have a smooth appear- 
ance on the upper surface, and are slightly greyish 
on the lower surface, being pointed and of an 
ovate shape. The fruits are long cylindrical pods 
from 9 to 18 inches long, and sometimes more. 
The pod is divided into partitions inside, and 
the seeds are found in these. Along with the 
seeds a black pulpy substance is found which is 
of a peculiar sweet taste. 
The young leaves are cut into small shreds, and 
a dry curry (mellun) is made with scraped 
coconut and other curry stuffs. The whole plant, 
including the leaves, have slight purgative pro- 
perties. The bark as well as the root is given in 
native medical practice in cases of rheumatism. 
The heartwood of the tree forms a good timber 
and is used for various purposes. 
26. Cassia Occidentalis, L. ; Sin. Peti-tora. 
This plant is very abmidant in the unculti- 
vated places of the lowcountry. Though found 
in uncultivated places, it always prefers patches 
of land which are fertile. The plant is very small and 
much branched. Theleaves are compound pinnate, 
and the leaflets are smooth. In shape the leaf- 
lets are obovate, having the ends round and the 
margins entire. The,flowers are yellow, and the 
pods which are cylindrical, are thin and from 3 
to 4 inches long. The seeds are rounded in appear- 
ance and long. 
The tender leaves are made into dry curries, 
and sometimes they are boiled and eaten along with 
coconut, &c. The seeds roasted and pounded are 
used like coffee, and are said to possess medi- 
cinal properties. The leaves have cooling 
properties, and are used, boiled in water for 
fomenting in cases of swellings and wounds. The 
seeds also are used externally in skin diseases. 
The decoction of,the^leaves is held as a good remedy 
for purifying the blood. The dry twigs are used 
in making brooms. 
27. Cassia Tora, L. ; Sin. Peni-tora. 
This plant resembles the one described above in 
. its habits, but the plants themselves are a little 
more erect and less branched. They grow to the 
height of about 3 feet, and the pinnate leaves are 
attached to a dark coloured stem. The base of 
the petiole is swollen at the place of attachment. 
The same character is observed in the attachment 
of the leaflets. The leaflets are pointed and ovate, 
and the veins show a black streak. The flowers 
are yellow and are borne in panicles. 
The tender leaves are used in making a dry curry. 
The seeds are externally applied in skin diseases, 
and the leaves are used in cases of cough. 
