Sept, i, 1897.) 
THE TROPICAL AGRICULTURIST. 
its head part is placed the mouth, in the middle of 
small sucker, and at the point where the head joins 
the flat body, on the lower surface, is another sucker. 
The colour is pale brown. The eggs, which are 
brownish and excessively minute, are passed dow’n 
from the liver to the intestines, and thus distri- 
buted with the droppings of the infested animals. 
If the eggs fall in favourable circumstances for 
hatoiiing (that is, warm weather on wet and 
marshy ground, or are washed into ditches or 
ponds), the embryo within develops in a period 
which may be of from two or three weeks to two 
or three months, according to temperatrrre ; then 
the contained embryo pushes off one end of the egg- 
shell, and swims away with great rapidity and ac- 
tivity. This embryo is described by Prof. A. P. 
Thomas, in his minutely recorded observations 
from life of this infestation, as being only 
about l-200th of an inch in length , that is, almost 
too minute to be visible to the naked eye, and in 
shape not unlike a sugar loaf. In the centre of the 
largest end is a peg-like projection which is used 
as a boring tool, and can be withdrawn, or greatly 
thrust out, at pleasure. The embryo darts and 
circles about in the water, large and foremost, and 
if, in the course of its movements, it meets with 
the water snail (Lininceiis truncatulus), it at once 
commences operations. It inserts its borer, and, 
spinning round and round on itself in the water so 
as to work the point in like a centre -bit, squeezes 
its way into the substance of the snail. Here the 
embryo settles into almost still life, and changes 
into an oval form, which, when complete, is known 
as a sporo-cyst, that is, a “cyst,” or a bag or 
bladder, of germs. Within this bag, so to call it, 
about ten germs develop, known as “redise.” Each 
redia as it is developed makes its way out of the 
sporo-cyst, and being furnished with a mouth and 
intestine, and two projections that answer the pur- 
pose of legs, it feeds on, and makes its way about 
within, the liody of the snail. 
Up to this point it will be seen there are four 
distinct stages of fluke life — the egg : the free swim- 
ming embryo ; the quiet form of the sporocyst, al- 
tering to a mere bag of developing germs ; and the 
germs called rediie, free from the bag, and feeding 
on the snail, which ultimately (for the most part) 
sinks under the parasitic attack. Continuing the 
history from the same observations, it is shown 
that in each of these rediae there form (as in the 
sporo-cyst before mentioned) a number of germs, but 
different to these in shape. The germs (the redise) 
that formed in the sporo-cyst are long and narrow, 
about the sixteenth of an inch in length, and about 
one-fifth of their length in width ; but the germs 
which form within the redi® are exceedingly like 
tadpoles, being oval and flat, and furnished with 
long slender tails more than twice the length of the 
body. 
These “fluke tadpoles,” so to call them, are tech- 
nically called cercari®, meaning animals with tails. 
On the escape of each cercaria from the redi® in 
which it was formed, it makes its way from the 
body of the snail into the water (if in a pond or 
ditch), but shortly attaches itself to water plants, 
or whatever may be accessible. There it draws it- 
self up into a round ball, exudes a gummy secretion, 
wags its tail violently, till at last the appendage, 
which has now ceased to be useful, is thrown off, 
and the gummy substance hardening, the cercaria 
remains within the covering as a little white spot 
on the plants, or on the locality to which it has 
attached itself. It is mentioned, however, by Prof. 
Thomas that “ if the infested snails are crawling 
on the margin of a ditch or over a damp field, the 
cercari®, on leaving the snail, at once proceed to 
form their envelopes or cysts at the bottom of the 
grass, and so attach themselves to the stalks or 
leaves near the roots.” The next step completes the 
circle of infestation. When the grass, to which the 
white speck-like cysts containing the young liver 
flukes adhere, is eaten by the sheep, or other suit- 
able hosts (as rabbits or hares &c.), the young fluke 
comes out of the covering, and passes to the liver 
151 
of its host, increasing in bulk, after being swallowed, 
from about the eightieth of an inch, to the adult 
length of an inch or an inch and a third. 
Amongst methods of prevention and remedy men- 
tioned by Prof. Thomas are the following : — 
Care must be taken to avoid introducing eggs 
of the fluke either with manure, or with fluke sheep, 
or in any other way. Rabbits and hares must not 
be allowed to introduce the eggs. 
Cressings of lime, or salt, should be spread over 
the ground at the proper seasons, to destroy the em- 
bryos, the cyst of the fluke, and also the snail, which 
acts as ‘ host. ’ 
Sheep must not be allowed to graze closely, for 
the more closely they graze, the more fluke germs 
will they pick up. 
When sheep are allowed to graze on dangerous 
ground, they should have a daily allowance of salt, and 
a little dry food. 
Amongst the details of treatment, of which the 
above is an abstract, is the observation : — “ The 
freedom from lot of sheep feeding on salt marshes 
is well known, and is now shown to be due to the 
poisonous action of the salt on the embryos, sporo- 
cyst, redia, cercaria, and cyst, and to its similar 
action on Limnaus tmncatnlus itself. Even a weak 
solution of salt in water (containing only | per cent, 
of salt) proves fatal to this snail. 
This principle of prevention would be especially 
applicable where (as in the instance, before men- 
tioned, in West Gloucestershire) it was the custom 
to have exceedingly small ponds or cisterns of 
mason work open to the field on one side and very 
shallow, and only a few yards square. Prom the 
immense quantity of weed or grass growth in or at 
the edges of these so-called “ cattle-drinks, ” and 
sometimes the quantity of mud (which is stated to 
be the especial place of deposit of spawn of the 
Livmceus truncatulus), there was every circumstance 
that was good for shelter, or propagation, of either 
tmncatulus or iireger ; and in circumstances like these 
a very small outlay on salt would carry destruction 
with it to the snails and the fluke embryos in the 
water. Clearing the various vegetable trash, and 
sprinkling some salt on the mud and into the water, 
would cost little, and from the details given would, 
in many cases, strike in emhyo at infestation which 
presently, when dispersed over the field, would be 
far more difficult to deal with. 
THE END. 
ARECA-NUT CULTIVATION IN INDIA. 
IN THAN A. 
The betel-nut is grown largely in Thana, Bombay. 
The best nuts are carefully selected in October, and 
dried in the sun ; unhusked nuts are considered best 
for seed. They are planted in a well-ploughed plot 
of land in pits three inches wide and three inches 
deep, and at a distance apart of from six inches to 
a foot. For the first three months the young palm is 
watered at least every fourth day, and afterwards 
every third day. When the plants are a year or a 
year and-a-half old they are fit for planting out. 
The selling price of young plants varies from 6 pies 
to 1 anna. 
The betel palm usually grows in red soil, but it 
flourishes best in sandy soil that remains moist for 
sometime after the rains. Before planting the young 
palm, the ground is ploughed, levelled and weeded, 
and a water channel is dug six inches deep and a 
foot and a-half wide. The pits 9 inches deep and two 
feet wide are dug at least four feet apart, nearly full 
of earth, but not quite full, so that water may lie in 
them where the soil allows ; plaintains are grown in 
the beds to shade the young palms. Except during 
the rainy season, when water is not wanted, the young 
trees are watered every second day for the first five 
years and after that every third or fourth day. During 
the rains the manure is sometimes given. 
The cost of betel-nut cultivation in Thana is calcu- 
lated as follows : — An acre entirely given to betel 
palms would, it is estimated, hold 1,000 trees. The 
