396 
THE TROPICAL AGRICULTURIST. [Dec. 1 1900. 
other words, are the two sexes found in separate 
individuals, or are they all iemale or hermaphrodite 
capable of breeding by self -fertilisation. Now, accor- 
ding to Dr. Kelaart, who is universally acknowledged 
to be the highest authority on the subject, there 
is DO proper distinction between the two sexes, except 
in the contents of the owariwm or egg-bag, which m 
97 or 98 per cent contain ova at all stages o£ 
growth even from birth, and only in one or two per 
cent contains the fluid essential for cross-fertilization 
and no ova at all. These oysters then represent 
the male individuals, though there is nothiug 
in the external coat, or internal structure to dis- 
tinguish them from the others. The practical im- 
portance of this fact comes in with the light it 
throws on a possible frequent cause of the disappear- 
ance of oysters from old oyster beds. For, if cross fer- 
tilization be essential to the production of a healthy 
progeny as Darwin has established and large colonies 
of such progeny growing together are necessary to form 
a productive "baud," as Kelaart has shown, the destruc- 
tion of the few males by any acoidentp>-l cause, may 
suffice for the extinction of an entire batik of oysters. 
Mr CoUett himself to whom I referred this point before 
the lecture was good enough to explain to me that he 
believed that the female oyster has it in her power 
to change her sex, as often as she chooses, a vv-onderful 
fact, if it be the case; only it is to be hoped that 
Nature haslimited this marvellous power of self-trans- 
formation to the oyster, which exceeds, 1 think all that 
the new woman with all her claims for woman's rights 
could imagine in her wildest dreams. But I believe 
even Mr. Oollett is not quite sure on this point, so 
that one of the most important problems connected 
with the life history of this biva.lve still remain to be 
solved by science. Another point on which I should 
wish to be enlightened by Mr. Collett is with regard 
to the formation of pearls. Ha has given in his 
adhesion to the parasitic theory and even quotes 
Dr. Kelaart in support of it — but a careful reading 
of Dr.Kelaart's reports, both of '57 and '58, seems to me 
to show that while he only countenanced the parasitic 
theory as accounting for exceptionally, as it were, the 
formation of pearls in some cases, he never abandoned 
his original theory made from actual observation 
that the true nuclei of true pearls are the ova of 
the pearl oyster itself as a rule, and only exceptionally 
the ova of parasites that enter its body with its food, 
while only inferior and irregular false pearls result from 
the artificial intrusion of particles of sand, etc., to 
serve as nuclei. So far as my reading goes Dr. 
Evarard Home in the last century was the first to 
advance the theory of abortive ova being the nuclei 
of pearls, and Dr. Kelaart at first accepted it with a 
modification by saying that it was not the ova which 
are left bahin 1 in the ovarium but those which 
escape through the over-distended coat of the egg- 
chamber, when it ruptured as it may easily do near 
the hinge, when they would bury themselves in the. 
interstioes of the mantle and so become the nuclei of 
pearls. Bat in his later report of 1859 he says 
he wasso fortunate as to find an entire ovarium charged 
with no less than 32 pearls, and still another which 
he did not open, but which appeared to contain as 
many more — thus completely confivmiag Dr, Home's 
theory. Both these specimens he sent to Dr. Owen, 
and are now to be seen in the Museum of the Col- 
lege of Surgeons in London. How, or whence the 
nacre, or peai-l-lining substance was formed 
for these pearls in the ovary, Dr Kelaart would not or 
could not determine, but he supposes with great probabi- 
lity — what science at the present day can easily con- 
firm — that the ovarium membrane can secrete it. For 
it is a curious circumstance that human pathology 
afforda analogous illustrations, both of abortive ova and 
even embryos becoming the centres of new and varied 
forms of all growth--and soraetimss of concretions 
of an intensely bard character known as lithopadia — 
but still more curiousiy that the lining membrane 
ef the ovary from which proceed thcso metamorphosed 
but uaimpregaat^:d iva sometirnes secretes the most 
ex.traordiuary structures such as bones, teeth, hair 
&c,, wit'nout any trace of embryonic formation, which 
may even gi ow from the ovary of the embryo itself, and 
become serious pnthological tumours in after-life, 
It is unnecessary for me to point out tlie bearing 
that this theory of Dr. Kelaart's his on the proper 
method of oyster culiure. Entirely opposed as it is 
to that now proposed, based on the theory that con- 
ditions which favour the entrance of parasites which 
foster disease are the best for pearl formation. In 
conclusion, I am sure that Mr. CoUett will do Dr. 
Kelaart the justiceto ackuowledge that although there 
may be no ponderous monograph in any language on 
the natural history of the oysters — and a great 
book, according to the great proverb, is not seldom 
a great evil, — his reports on the subject, though written 
nearly 50 years ago, are as complete as far as they go 
on the subject as could be desired. There has been little 
that is new that has been discovered by naturalists 
since, to supply the desiderata Mr. Collett refers to in 
his paper. I say this, because I do not think Ceylon has 
sufficiently acknowledged the debt of gratitude she 
owes Dr. Kelaart for his researches, in conneitiou with 
the Ceylon Pearl Oyster. One of the earliest sons of 
the soil — belonging to the Burgher community, who 
having secured a British degree, entered the' Army 
Medical Service, where his reputation as a scientist 
generally — as Geologist, as Botanist, as Zoologist, es- 
pecially as a Conchologist in connection with the 
subject of Pearl Oysters — bas received the recognition 
of the whole scientific world. (Applause.) 
After the vote had been carried by acclamation, 
Mr. Collett, in risino; to reply, said he would 
like to answer one or twy points raised by Dr. 
VanDort. Firstly, he wouhl refer to Sir W 
Twyiiam a.s regards the pathological and zoolo- 
Etieal .study of the oyster ; that authority said 
that our knowledge in this respect was still 
almost nil. His own paper had b^en entirely 
theoretical, summarising tlielates:. writings on the 
subject, and he (the speaker) liad taken it up 
more as a zoological recreation for a busy planter 
tnan with any scientilic experience of the subject. 
Dr. VanUort had expected him to put into the 
paper more than he (Mr. Collett) had intended. 
He was verj gratilied at the reception his paper 
had received ; he could feel that if it had done 
nothing else, it had elicited a most interesting 
discussion and he thanked them all for their cordial 
vote of thanks. (Applause). 
The Bishop of Colombo proposed a very hearty 
vote of thanks to His Excellency for occupying the 
chair that evening. In any assembly of the inhabi- 
tants of Ceylon they were very much pleased to have 
the Governor with tbeni and the members of that 
Society felt that in a prirticular degree. They 
were very grateful to His Excsllency for having made 
the effort to come out on that wet night. Cynical 
outsiders might say that a meeting of the Hoyal 
Asiatic Society would be the very place to come 
to on a wet night, because they would be sure to 
find something dry. (Laughter.) Such a person 
would have been hopelessly wrong, on an occasion 
like that evening. He was not aware to what 
extent His Excellency gave a personal study 
amidst his many vocations to those matters 
which particularly occupied them as a learned 
Society, but it was quite certain that 
in one branch of their proceedings H.E. 
encouraged them by his pretence tlat 
evening as in that part of their pro- 
eee.lings in which they tried to lay or develop 
that scientific basis upon which alone could be 
soundly erected any structure of utility in any 
work, especially of production of any kind. 
And their Governor had shown them by the 
intere.st that he had takeu and the efforts he 
