Nov.- 2, 1903.] THE TROPICAL 
AaHtCULTURlST. 
333 
PEARL FORMATION IN, |THE CEYLON 
PEAKL ^OYSTER. 
DR. HEKDMAN'S PAPERS AT THE 
BRITISH ASSOCIATION. 
A paper ou "Peail-Formatioa iu the Ceylon 
Pearl-Oystei," conciibuDed by Professor Herdinaa 
F KS, ami Mr James Hornell, and read before the 
British Association on Sept. 16th, stated that tliey 
had had two cruises of several weeks each arnonfjsc 
the pearl-oyster banks in the Gulf of Manaar, 
and had had the experience of the three con- 
seciiiive inspections of March and November, 
1902, and March 1903, and also the successful 
fishery of 1903, from which to draw conclusions. 
Many hundreds of oysters had been examined, 
and large numbers of pearls had been decalcified. 
As a result of this work they had come to the 
conclusion that there were several distinct causers 
that led to the production of pearls in the Ceylon 
pearl "oyster" :— (I) Some pearls or pearly ex- 
crescences ou the interior of the shell were due to 
the irritation caused by Clione, Leucodore, and 
other boring animals ; (2) niiuuDe grains of sand 
and other inorganic particles only formed the 
nuclei of pearls under exceptional circumstances. 
Probably it was only when thesbell was injured — 
e.g., by the breaking of the "ears," thus 
enabling sand to gee to the interior — that such 
particles supplied tue irritation that gave rise to 
pearl«foraiation ; (3) many pearls were found in 
Dhe muscles, especially at the lavator and pallial 
insertions, and these were foimed around minute 
calcareous concretions, the " calcospherules " 
which were produced iu the tissues and formed 
centres of irritation ; (4) most of the fine pearls 
found free in the body ot the Ceylon oyster con- 
tained the remains of Platyiiehninchian parasites, 
so that the soimulatiuu which led to the formation 
of an " Orient " pearl was, as had been suggested 
by various writers iu the past, due to the pre- 
sence of a minute parasitic worm. In all cases, 
whatever its nucleus might be, the pearl, like the 
nacre, was deposited by an epithelial layer, These 
pearls might be conveniently classlhed as (1.) 
AinpuUar-pearls, where the nucleus and resulting 
pearl lay in a pouch or ampulla of the ectoderm 
projecting into the mantle ; (11.) Muscle-pearls, 
lormed around calcospherules near the insertions 
of muscles ; and (III ) Cyst-pearls, formed 
around encysted parasites. The parasite in the 
case of tbe majority of the cyst-pearls of Ueylon 
was the larva oX a Cestode whicu appeared to 
be new and would be described under the name 
Tetrarhynchus unlonlfactor. The younger larval 
stages bad been found free-swimming in the Gulf 
of Manaar, and ou the gills of the oyster ; later 
stages were common in the liver, mantle, and 
gills, and a more advanced condition was found 
in the Pile-hslies, Ralistes mlcls and B 
stellatus which fed upon the oysters, The 
sexually mature Cestode had not yet been found, 
but it luigUt be expected to occur either iu one 
of tUe large Eilasmobranchs (such as Trygon 
Darnak), which abounded ou the pearl-banks, or 
in one of the smaller cetaceans which might also 
feed upon such tishes as Ballstes. 
Pioiessor Herdman also discoursed on " A 
Phosphorescence Phenomenon in the Indian 
Ocean." He described how, during his recent ex- 
pedition to Ceylon, as they lay ac anchor In the 
Golf of Manaar, ou March liith, 1902, about 9 p.m., 
(he sea was soen to be dotted with bright piios- 
phorescent lights of considerable size singly placed 
at some distance apart. These for over an hour 
continued to glow with a pulsating appearance in 
harmony— all shining brightly attliesame moment, 
and then all flickering out together, to reappear 
simultaneously a few seconds later. On going 
out at once with a net, a sample of the [il uiklon 
was obtained, but it was not certain that any of 
the pulsating forms had been caught. The gather- 
ing contained Sagltta (very many) Appendicularia, 
Copepoda, several common species, and S.ipphirhina 
sinuicauda, Pontella fera, Calocaiauus pavo, 
and some smaller forms, along with half a dozen 
1 in. long Heteronereids of a reddish-brown colour. 
The light was thought to be probably due to the 
last-named, but the matter, however, could not 
be definitely ascertained at the time, and the above 
explanation was only suggested. —London Times, 
Sept. 17. 
Mr. J LOMAS, on September 14th, in a paper on 
* Polyzoa as Rock-cemencing Organism?,' described 
the composition and formation of ab ut 20 samples 
of 'calcretes,' which were among the specimens of 
sea-bottoms recently brought from the Gulf of 
Manaar by Professor Herdman. They were broken 
off by pearl-divers from the parent masses, which 
formed rocky platforms, locally called ' paars,' in 
many parts of the gulf. They all occurred in 
shallow water at depths varying from 2^ to 10 
fathoms. The majority of the specinnins were 
sandstones cemented by carbonate of lime, but 
occasionally compact limestones, sometimes phoa- 
phatlc, and coral rock were brought to the surface. 
All the stones were thickly encrusted with polyzoa 
nuUlpores, wormtubes, .sponges, and other marina 
organisms. While the Importance of nullipores as 
agents in binding grains of sand had been recog- 
nised, the work of polyzoa so readily broke up and 
lost their structural characters that it was only 
when very recent samples were at hand that criteria 
could be obtained determining tbelr former 
presence. Mr Loinas then described in detail the 
geological and zoological formation of these 'cal- 
cretes,' determined by examination of thin slices 
or sections of the calcrete with recent colonies on 
the outside. — London Times, Sept. 15. 
COTTON GROWING IN THE WEST INDIES, 
MEETING AT THE COLONIAL OFFICE. 
A conterence was held yesteniay at tlie Colonial 
Office to consider ihe question of the development 
of cotton growing In tue West Indies. The Duke 
of Marlborough, Under Secretary tor che Colonies, 
presided. The lollowing Colonial representatives 
were present : — Sir P Hodgson, Barbadoes ; Sir 
Gerala Strickland, Leeward islands; Sir C Knollys, 
Trinidad; Sir Robert Llewellyn, Windward Islands; 
Mr Ash more, British Guiana, together with Mr. 
Lucas and Mr. Pearson of the Colonial Office ; 
Mr Dobree, chairman of the Colonial Bank ; and 
Sir Alfred Jones, president ; and Mr J C Atkins, 
secretary, representing the British Cotton Growing 
Association. Cotton growing In the West Indies 
is being taken up very euergetlcally, and there 
is every prospect of a prosperous industry being 
establisned in the various Islands, The Governors 
are doing all In their power to ^courage the move- 
ment, and substantial assistance has been rendered 
by the British Cotton Growing Association who, 
in addition to giving a large sum to be dis- 
tributed in prizes, have provided machinery for, 
