H E L M I N 
generally larger, and of a finer colour, than in the fe- 
cond and third ; which two valuable qualities are like- 
wife found in that which is brought from a.lefs depth, 
compared with that which is.fifired up much deeper. 
The greateft height to which it grows is near a foot, 
and its ufuai thicknefs is that of the little finger, and 
fomewhat lefs than’that of the coafts of Trapani and 
Barbary ;• but the latter are exceeded by the Mcflinefe 
in vividnefs of colour. Thefe differences, according tq 
the account of the filhermen, arife from their coral-be¬ 
ing produced in a fea which is kept in continual agita¬ 
tion, from the furface to the bottom, by the current and 
the winds. The filhermen divide the trail in which 
they fifii into ten parts. Every year they fifii only in 
one of thefe parts, and do not fifii in it again till ten 
years are elapfed. This interval they think necefiary 
for the coral to acquire its full growth in height and 
confidence. When they tranfgrefs this law, they find 
the coral fmaller, and of lefs confidence ; and the inten- 
fity of the colour is always in proportion to the number 
of years they have defided from fifiiing. When the ten 
years have elapfed, they believe that the coral no inore 
increafes in height, but only in thicknefs; which, how¬ 
ever, has its limits. I'nfadt, they have obferved, that 
the corarfilhed up near San Stefano, a place where none 
had been fought for in the memory of man, though it 
was of a very bright colour, was not higher than the or¬ 
dinary coral, though it exceeded it by one-third in thick¬ 
nefs. The number of diips ufually employed in this 
fidiery is eighteen or twenty, each of which is ufually 
managed by eight men. The quantity of coral procured, 
amounts annually-to about twelve Sicilian quintals. 
In the cortical and fofid parts of the white corals, 
Spallanzani obferves, the orifices of the cells being oc- 
to-radiated like thofe in the red, appears to be a proof 
that the polypi in both are of the fame ftruCture. That 
coral is loft in the fea, and hardens when it comes in 
contact with the air, was the opinion of the ancients; 
but this has been proved fallacious by the obfervations 
of the moderns. The coral-filhermen-of Medina, who 
derive all their knowledge from experience only, are 
convinced that this opinion is erroneous ; buftheyaffert 
that coral which has not attained maturity has not that 
degree of confidence whicli it acquires when arrived at 
its full growth. The truth of this podtion Spallanzani 
was not able to afeertain, as, for.that purpofe, it would 
have been neceffary to cad the net in one of thofe ten 
parts of the drait in which it is prohibited by the law 
to fifii till the expiration of the ten years preferibed. 
Yet the rules of analogy, derived from what is obferved 
' in all animals and vegetables, incline him to favour this 
opinion. It is agreed however by the filhermen on the 
coads of Barbary, and alfo by thofe of Medina, Sardi¬ 
nia, and Cornea, that the deeper- they defeend into the 
lea, the (mailer i s the coral. Donati_ obferves, that the 
broken and detached branches of coral, like all polypi, 
will continue to live and multiply in the fea ; which Spal¬ 
lanzani allows to be the cafe, provided they meet with 
a firm point of fupport to which they can attach thenv- 
felves with their vifeous humour. Otherwife, if they 
fall on the moveable fand, they becorne the fport of the 
waves, and he has no doubt but they mud peridi. The 
Mefiinian filhermen appear to be well acquainted with 
the true generation of coral; and they told Spallanzani 
that they had frequently obferved, on hard fubltances 
drawn from the bottom of the fea, the firlt principles of 
Coral beginning to germinate ; which they deferibe as 
having the appearance of a red fpot, with a button or 
bud implanted in thofe matters, evidently the ovum or 
egg of the parent polype thus depolited j fometimes 
tender and fragile, and fometimes hardened, and.of the. 
colour and nature of ordinary coral. They are like- 
wife acquainted with thofe branches of coral which, 
when filhed up, are fometimes found perforated by li- 
T H O L O G Y. 35$ 
thophagous worms, mentioned by Vitaliani and Marff- 
gli. Their nets had frequently brought them up, either 
from the bottom of the fea, from caverns, or the fides 
of rocks; and thefe perforated corals Were found fome¬ 
times broken in the trunk, where the perforations are 
mod frequent; and at other times attached to fome 
body, which ferved them as a-bafe. They were of opi¬ 
nion that thele corals were thus perforated, beCaufe 
they were dry ; and this drynefs, they imagine, pro¬ 
ceeds either from age, or their having been broken from 
their root by fome fifii, or by a part of a rock falling on 
them ; or pollibly by the coral nets, which do not al¬ 
ways bring up all the branches of coral they'loofen from 
their roots. 
In order to afeertain the true nature of the fubffance 
wherewith corals are formed, and their approximation 
or affinity to fiiell and bone, C. Hatchett, efq. F.R.S., 
has recently fubjedted feveral of the genera to cheniical 
inveftigation. The zoophytes to which his analyfis and 
enquiries were applied, were feveral fpeeies of Madre- 
poraand Millepora, one fpeeies of Tubipora, the Fluff 
tra foliacea, the Corallina opuntia, two fpeeies of Ifis, 
feveral of Gorgonia, two of Antipathes, and feveral of . 
Sponges, and alfo of Alcyonium. The firft object was 
to afeertain, in thefe animal fubltances, the prefence of 
carbonate and phofpjiate of lime, which are the mate¬ 
rials employed by nature to communicate rigidity and 
hardnefs to (hell and bone ; and then to examine how the 
hardening or olfifying principles are fecreted and depo- 
fited. 
The hardening fubftance of the Madrepores and Mil- 
lcpores, (with only one exception,) appears to be car¬ 
bonate of lime ; and they refemble fhells in being form¬ 
ed of a membranaceous fubftance, thus hardened. The 
only difference is in the mode according to whicli thefe 
materials are employed. The *Tubipora mufica refem-~ 
bles the fore-mentioned fubltances. With refpedt to the 
Fluftra foliacea and Corallina opuntia, only a fmall por¬ 
tion of phofphate is found, mixed with the carbonate 
of lime. The Ills ochracea and hippuris are formed of 
regularly organized membranaceous, cartilaginous, and 
horny, fubftance's ; hardened, in the laft fpeeies, merely 
by carbonate of lime, and in the former with the addi¬ 
tion of a very fmall portion of phofphate of lime. The 
hardening fubftance of the Gorgonia nobilis is found to 
be carbonate of lime, with a fmall quantity of phofphate ; 
and the matter conftituting the membranaceous portion 
is partly gelatinous, and partly membrane completely 
formed, fo as to cover the Item in the manner of a tube.* 
The other Gorgoniae,'viz. the ceratophyta, flabellum, 
fuberofa, peftinata, and fetofa, are compofedof a horny 
Item, and a cortical fubftance, by which it is coated. 
The Items afford a quantity of phofphate of lime, with 
fcarcely any trace of carbonate, and the cortical part 
cOnfifts principally of carboriite of lime, with little or 
none of the phofphate. 
The Antifiathes are found to be little, if at all, dif¬ 
ferent from the horny Items of the Gorgonise ; and the 
various fponges are completely formed by the fame 
membranaceous or horny fubftance, varied by modifica¬ 
tions of a more delicate conftrudtioji, rather than by any. 
eftential difference in compofition. The Aloyonia are 
found to be compofed of a foft flexible, membranaceous 
fubftance, fimilar to the cortical part of the Gorgonia 
fuberofa, and iri like manner fiightly hardened by car¬ 
bonate, mixed with a fmall portion off phofphate of 
lime. From thefe fa£ts Mr. Hatchett concludes, “ that 
the varieties of bone, Ihell, coral, and the numerous 
tribe of zoophytes with which the laft are connected,, 
only differ in compofition by the nature and quantity of 
the hardening or olfifying principle, and by the ftate of 
the fubftance with which it is mixed or connected.” 
Thus, then, it is evident that coral is the bone of. zoo¬ 
phytes, analogous to bone in all other .animals. But 
.the 
