THE TROPICAL AGRICULTURiST. 39 
July 1, 1903,] 
pearls, only do so; in our cxperieuce, in exceptional 
circunislaoces. Out of the many pearls I have 
decalcified, only one CDUwiiiied in its centre what 
was up.'loabtedlj a grain of siind ; and from !S"i 
Hornell's notes, tuken since I Id t Ceylon, I quote 
the following iiassap;e, showini^ that he has had a 
similar experience : — 
"February 16, VM3- Ear-i)carh: Of two de- 
calcified, one from the anterior ear (No. 148), 
proved to have a minute quart z grain (micro, pre- 
paration 25) as nucleus.'' 
It seems proballe that it is only when the shell 
is injured, as, for example, by the breakiufr otf 
or crushing of the projecting " ears,'' thereby 
enabling some fine saiid to gain access to the 
interior, that such inorganic particles sup])ly the 
IRRITATION WHICH GIVKS K18E TO VEAllh 
FOBMATION. 
The majority of the pearls found free in the 
tissues of the body of the Ceylon oyster contain, 
in our experience, the more or less easily recoir- 
nisahle remains of Platyelmian parasites ; so that 
the stimulation which causes eventually the for- 
mation of an " orient " pearl is, as has been 
suggested by various writers in the past, due to 
infection by a minute ^lowly worm, which becomes 
encased and dies, thus justifying, in a sense, 
Dubois's statement that—" La plus belle peile 
n'est done, en definitive, que lebrillant sarcophage 
d'un ver" (Comptes rendus, October 1-1, 1901.) 
[The lecturer then dealc with the work of l)r. 
Kelaart (1859), to whom belongs the honour of 
having first connected the formation of pearls in 
the Ceylon oyster with the presence of Vermean 
parasites, Filippi, Kukenmeister, Moebius, Hum- 
bert, Garner, Thurstonj Giard, Seurat, Jameson, 
and finally Dubois— up to January, 1903.] 
■We have found, as Kelaart did half a century ago, 
that in the Ceylon pearl oyster there are several 
difterent kinds v)f worms commonly occurring as 
parasites, and we shall, I think, be able to show in 
our final report that Cestodes, Trematodes, and 
Nematodes are all concerned in pearl formation, 
Unlike the case of the European mussels, however, 
we find, so far, that in Ceylon the most important 
cause is a larval Cestode of the Tetrarhynchus 
form. Mr Hornell has traced a considerable part 
of the life-history of this parasite, from an early 
free-swiniming stage to a late larval condition in 
the file fish (Balisfes mitis) which fre- 
quents the pearl banks and preys upon 
t'le oysters. We have 
NOT YET SUCCEEDED IN FINDING THE ADULT, 
but it will probably prove to infest the 
sharks or other large Elasmo branches which 
devour Balistes. It is only due to my ex- 
cellent assistant, Mr James Hornell, to state 
that our observations on pearl formation are 
mainly due to him. During the comparatively 
limited time (under three months) that I had on 
tlie banks, I was mainly occupied with what 
seemed the more important question of the lite- 
conditioQS of the oyster, in view of the frequent 
depletion of particular grounds. It is important to 
note that these interesting pearl-formation para- 
sites are not only widely distributed over the 
Manaar banks, but also on other parts of the 
coast of Ceylon. Mr Hornell has found Balistes 
with its Cestode parasite both at Trincomalie and 
at Galle, and the sharks also occur all round the 
ialand, so that there can be no question as to the 
probable infection of oysters grown at these or 
any other suitable localities. 
There is still, however, much to find 
out in rcgaul to all these jjoints, and other 
details affecting the life of the oyster and the 
prosperity of the pearl fisheiie.=. Mr Hornell and 
I fire still in the middle of our investigations, 
and this must le regarded as only a preliminary 
statet.!ent of results which may have to be corrected, 
and I hope considerably extended in our final report. 
It is interesting to note that tha Ceylon Govern- 
ment Gazette of December 22 last announced a 
j)earl fishery, to Ci^mmence on February 22, during 
which the following banks would be fished : — 
The South-East Clieval Pyar, estimated to have 
49 miiliou oysters. 
The East Cheval Paar, with 11 niilliona. 
The INorth Bast Cheval Paar, with 13 millions. 
ThePeriya Paar Kerrai, with 8 millions — making 
in all more than 80 million oysters. 
That fishery is now in progre.=s, Mr Hornell is 
attending it, and we hope that it may result not 
merely in a large revenue from pearls, but also in 
considerable additions to our scientific knowledge, 
As an incident of our work in Ceylon, it was 
found necessary to fit up 
THE SCIENTIFIC MAN'S WORKSHOI' 
— a small laboratory on the edge of the sea, 
with experimental tank=, a circulation of sea-water 
and facilities for microscopic and other work. For 
several reasons [discussed in the lecture] we chose 
Galle at the southern end of Ceylon, and we have 
every reason to be satisfied with the choice. With 
its larg'3 bay, its rich fauna and the sheltered 
collecting ground of the lagoon within the coral 
reef, it is probably one of the b;st possible spots 
for the naturalist's work in eastern tropical seas. 
In the interests of science it is to be hoped then, 
that the marine laboratory at Galle will soon be 
establijhed on permanent basis with a suitable 
equipment. It ought, moreover, to be of sufficient 
size to accommodate two or three additional zoO' 
logists, such as members of the staff of the museum 
and of the medical college at Colombo, or scientific 
visitors from Europe, The work of such men 
would help in the investigation of the marine 
fauna and in the elucidation of practical problems, 
and the laboratory would soon become a credit 
and an attraction to the colony. Such an insti- 
tution at Galle would be known throughout the 
scientific world, and would be visited by many 
students of science, and it might reasonably be 
hoped that in time it would perform for the marine 
biology and the fishing industries of Ceylon very 
much the same important functions as those ful- 
filled by the celebrated gardens and laboratory at 
Peradeniya for the botany and associated economic 
ptoblems of the land. W.A,H,—iVa<2t?-e, April 30. 
^ __ 
PRESEEVATION OP COCONUT TREES 
FROM PESTS IN F.JI , STATES, 
Annual Keport of Inspector for the 
Year 1902. 
I assumed my duties as Federal Officer under 
the Coconut Preservation Enactment on the Ist 
