Chap. 54.] 
PEAELS. 
431 
world; Perimula/^ also, a promontory of India. But those 
are most highly valued which are found in the vicinity of 
Arabia/^ in the Persian Gulf, which forms a part of the Eed 
Sea. 
The origin and production of the shell-fish is not very dif- 
ferent from that of the shell of the oyster. When the genial 
season of the year^^ exercises its influence on the animal, it is 
said that, yawning, as it were, it opens its shell, and so receives 
a kind of dew, by means of which it becomes impregnated j 
and that at length it gives birth, after many struggles, to the 
burden of its shell, in the shape of pearls, which vary accord- 
ing to the quality of the dew. If this has been in a perfectly 
pure state when it flowed into the shell, then the pearl pro- 
duced is white and brilliant, but if it was turbid, then the 
pearl is of a clouded colour also ; if the sky should happen to 
have been lowering when it was generated, the pearl will be 
of a pallid colour ; from all which it is quite evident that the 
quality of the pearl depends much more upon a calm state of 
the heavens than of the sea, and hence it is that it contracts a 
cloudy hue, or a limpid appearance, according to the degree of 
serenity of the sky in the morning. 
If, again, the fish is satiated in a reasonable time, then the 
pearl produced increases rapidly in size. If it should happen 
to lighten at the time, the animal shuts its shell, and the pearl 
is diminished in size in proportion to the fast that the animal 
has to endure : but if, in addition to this, it should thun- 
16 See B. vi. c. 23. JElian, Hist. Auim. B. xv. c. 8, says to the same 
effect, but calls it "Perimuda, a city of India." 
JElian, Hist. Anim. B. x. c. 13. It has been aheady remarked, in the 
sixth Book, that the ancients looked upon the Persian Gulf as forming 
part of the Erythraean or Red Sea. 
18 The pearl itself, Cuvier says, is nothing else but an extravasation, so 
to say, of the juices, whose duty it is to line the interior of the shell, to 
thicken and so amplify it ; and consequently, it is produced by a malady. 
It is possible, he says, for them to be found in all shell-fish ; but they have 
no beauty in them, unless the interior of the shell, the nacre^ or, as we call 
it, the mother of pearl, is lustrous and beautiful itself. Hence it is, that 
the finest of them come from the east, and are furnished by the kind of 
bivalve, called by Linnseus, " Mytilus margaritiferus," which has the mo^t 
beautiful mother of pearl in the interior that is known. The parts of the 
Indian sea which are mentioned by Pliny, are those in which the pearl 
oyster is still found in the greatest abundance. 
1^ All this theory, as Cuvier says, is totally imaginary. 
I 
