408 The Philippine Journal of Science 1921 
ditches, thus furnishing the growing plants on the beds with a 
constant supply of water. These plots are now ready for in- 
tensive cultivation and in the years to come will reveal the 
results obtainable on these low, otherwise useless, bottom lands 
when sufficient capital is available to clear the swamps and 
to control the waters. 
CARE OF THE DIKES AND BEDS 
After the land ig cleared and planted, some years will elapse 
before the region assumes its new aspect of a cultivated area 
(Plate 4, fig. 3). It never appears to have the regularity of a 
systematically planted western orchard, though some of the best 
Nakorn Chaisri pummelo groves approximate it (Plate 5,.fig. 1). 
The dikes, first thrown up as small embankments, gruadually 
settle and are then broadened and strengthened by the fill from 
the main canals, which almost every year are deepened or 
cleaned. These eventually assume the proportions of heavy 
embankments upon which grass or cultivated vegetation soon 
takes hold. Along the main canals thatched huts are built on 
piles, often with cement steps leading down to the water (Plate 5, 
fig. 2). Simple bridges made of bamboo, the trunk of a coconut 
tree, or perhaps a single board are placed across the stream. 
The earth at the base of the dikes is often held in place by 
the systematic planting of Bruguiera sexangula (Lour.) Pers., 
the roots of which endure constant flooding (Plate 5, fig. 3). 
The slope on the stream side of the dike frequently becomes an 
impenetrable growth; but an open strip, at least 60 centimeters 
in width, is maintained along the top as an attractive and 
useful walk. On the inside of this walk is the first bed of 
fruit trees (Plate 6, fig. 1). At some suitable place under the 
dike of the first bed there is laid the hollow trunk of a palm tree, 
through which water can pass from the canal to the ditches when 
the gate is opened (Plate 4, fig. 2). In some cases terra cotta 
pipe is used for this purpose. 
Within the diked inclosure are the beds of pummelo. These 
have become narrower and higher through the gradual process 
of widening and deepening the trenches (Plate 6, fig. 2). This 
operation of trenching is most skillfully carried out by Chinese 
laborers, as they best understand the methods whereby it is most 
efficiently done (Plate 6, fig. 3). During the heavy rains there 
is considerable washing from along the slopes of the beds (Plate 
7, fig. 1); therefore, the trenches are cleaned out each year, 
and the muck is smeared back over the beds. The whole region 
