Heaven-born and cradled in the deep blue sea, it is the purest of gems and the most precious.

The origin of pearls has been a fruitful subject of speculation and discussion among naturalists of all ages, and has provoked many curious explanations. Most of the early views—universally accepted during those centuries when tradition had more influence than observation and experiment—have no standing among naturalists at the present time. And although much information has been gained as to the conditions accompanying their growth, and many theories are entertained, each with some basis in observed fact, science does not yet speak with conclusive and unquestioned authority as to the precise manner of their origin and development.

Owing to the chaste and subdued beauty of pearls, it is not strange that poets of many countries have founded their origin in tears—tears of angels, of water-nymphs, of the lovely and devoted. Sir Walter Scott in “The Bridal of Triermain” refers to—

In one of his most lovely and consoling thoughts, Shakspere says:

And we quote from RÜckert’s “Edelstein und Perlen”:

In luster they so closely resemble the limpid, sparkling dewdrop as it first receives the sun’s rays, that the ancients very naturally conceived that pearls are formed from drops of dew or rain. The usual legend is, that at certain seasons of the year, the pearl-oysters rise to the surface of the water in the morning, and there open their shells and imbibe the dewdrops; these, aided by the breath of the air and the warmth of the sunlight, are, in the course of time, transformed into lustrous pearls; but if the air and the sunlight are not received in sufficient quantities, the pearls do not attain perfection and are faulty in form, color, and luster. However remarkable and even absurd this may seem at present, it appears to have been universally accepted for centuries by the most learned men of Europe as well as by primitive people who delight in the mystical and fantastic. This opinion was recorded in the Sanskrit books of the Brahmans and in other oriental literature. The classical and medieval writings of Europe contain numerous references to it; and it is found even yet in the traditions and folk-lore of some peoples.

In the first century A.D., Pliny wrote in his “Historia naturalis,” according to Dr. Philemon Holland’s quaint translation:

The fruit of these shell fishes are the Pearles, better or worse, great or small, according to the qualitie and quantitie of the dew which they received. For if the dew were pure and cleare which went into them, then are the Pearles white, faire, and Orient; but if grosse and troubled, the Pearles likewise are dimme, foule, and duskish; pale they are, if the weather were close, darke and threatening raine in the time of their conception. Whereby (no doubt) it is apparent and plaine, that they participate more of the aire and sky, than of the water and the sea; for according as the morning is faire, so are they cleere: but otherwise, if it were misty and cloudy, they also will be thicke and muddy in colour. If they may have their full time and season to feed, the Pearles likewise will thrive and grow bigge: but if in the time it chance to lighten, then they close their shells together, and for want of nourishment are kept hungrie and fasting, and so the pearles keepe at a stay and prosper not accordingly. But if it thunder withall, then suddenly they shut hard at once, and breed only those excrescences which be called Physemata, like unto bladders puft up and hooved with wind, no corporal substance at all: and these are the abortive & untimely fruits of these shell fishes.^[40]

Pliny’s views were probably derived from the ancient authorities of his time, particularly from Megasthenes, Chares of Mytilene, and Isidorus of Charace; and these curious fictions were incorporated by subsequent writers and influenced popular opinion for many centuries. With scarcely a single exception, every recorded theory from the first century B.C. to the fifteenth century evidences a belief in dew-formed pearls.

This theory is referred to by Thomas Moore in his well-known lines:

The Spanish-Hebrew traveler Benjamin of Tudela, in his “Masaoth” in Persia (from 1160 to 1173), wrote: “In these places pearls are found, made by the wonderful artifice of nature: for on the four and twentieth day of the month Nisan, a certain dew falleth into the waters, which being sucked in by the oysters, they immediately sink to the bottom of the sea; afterwards, about the middle of the month Tisri, men descend to the bottom of the sea, and, by the help of cords, these men bringing up the oysters in great quantities from thence, open and take out of them the pearls.”^[41]

From the “Bustan,” one of the most popular works of Sadi, the Persian poet (1190–1291 A.D.), Davie quotes:

Even the usually well-informed William Camden (1551–1623), in whose honor the Camden Historical Society of England was named, accepted the theory of dew-formed pearls. He stated that the river Conway in Wales “breeds a kind of shells, which being pregnated with dew, produce pearl.”^[42] Also, speaking of the Irt in county Cumberland, England, he said: “In this brook, the shell-fish, eagerly sucking in the dew, conceive and bring forth pearls, or (to use the poet’s word) shell berries (Baccas concheas).”^[43]

A recent letter from the American consul at Aden indicates that this view is held even yet by the Arabs of that region. In giving their explanation for the present scarcity in the Red Sea, he states: “There is a belief among them that a pearl is formed from a drop of rain caught in the mouth of the pearl-oyster, which by some chemical process after a time turns into a pearl; and as there has been very little rain in that region for several years past, there are few pearls.”

So firmly established throughout Europe was the belief in dew-formed pearls, that its non-acceptance by the native Indians of America excited the commiseration of the Italian historian Peter Martyr, in his “De Orbe Novo,” one of the very first books on America, published in 1517. He states: “But that they [pearls of Margarita Island on the present coast of Venezuela] become white by the clearnesse of the morning dewe, or waxe yelowe in troubled weather, or otherwise that they seeme to rejoice in fayre weather and dear ayre, or contrary-wise, to be as it were astonished and dymme in thunder and tempests, with such other, the perfect knowledge hereof is not to be looked for at the hands of these unlearned men, which handle the matter but grossly and enquire no further than occasion serveth.”^[44] Peter Martyr was distinguished for his learning, was an instructor at the court of Spain at the height of its power, and came in contact with the most enlightened men of Europe, consequently it may be assumed that he reflected the best opinions of his time.

It was not long before the aborigines of America were not alone in discrediting the views which had prevailed in Europe for more than fifteen hundred years. That practical old sailor Sir Richard Hawkins concluded that this must be “some old philosopher’s conceit, for it can not be made probable how the dew should come into the oyster.”^[45] A similar view is expressed by Urbain Chauveton in his edition of Girolamo Benzoni’s “Historia del Mondo Nuovo,” published at Geneva in 1578. From his reference to pearl-oysters on the Venezuelan coast, we translate:

Around the island of Cubagua and elsewhere on the eastern coast, are sandy places where the pearl-oysters grow. They produce their eggs in very large quantities and likewise pearls at the same time. But it is necessary to have patience to let them grow and mature to perfection. They are soft at the beginning like the roe of fish; and as the mollusk gradually grows, they grow also and slowly harden. Sometimes many are found in one shell, which are hard and small, like gravel. Persons who have seen them while fishing say that they are soft as long as they are in the sea, and that the hardness comes to them only when they are out of the water. Pliny says as much, speaking of the Orientals in Book IX, of his Natural History, ch. 35. But as to that author and Albert the Great and other writers upon the generation of pearls, who have said that the oysters conceive them by means of the dew which they suck in, and that according as the dew is clear or cloudy the pearls also are translucent or dark, etc., etc.,—all this is a little difficult to believe; for daily observation shows that all the pearls found in the same shell are not of the same excellence, nor of the same form, the same perfection of color, nor the same size, as they would or must be if they were conceived by the dew all at one time. Besides this, in many of the islands the Indians go fishing for them in ten or twelve fathoms depth, and in some cases they are so firmly attached to the rocks in the sea that they can be wrenched off only by main strength. Would it not be difficult for them to inhale the quintessence of the air there? It seems then that it is the germ and the most noble part of the eggs of the oyster which are converted into pearls rather than any other thing; and the diversities of size, color, and other qualities, proceed from the fact that some are more advanced than others, as we see eggs in the body of the hen.^[46]

The old theory of dew-formed pearls was illustrated even as late as 1684 on a medal struck in honor of Elena Piscopia of the Corraro family of Venice. This bore an oyster-shell open and receiving drops of dew, and underneath was engraved the motto “Rore divino” (By divine dew). Even yet one hears occasionally from out-of-the-way places—as in the instance reported by the American consul at Aden—of pearls formed from rain or dew, notwithstanding that there seems to exist absolutely no justification for it in scientific zoÖlogy.

Probably the most popular theory entertained from the fifteenth to the seventeenth century was that pearls were formed from the eggs of the oyster. This was intimated by Chauveton in the quotation above given, and it was also referred to by many naturalists.

In an interesting letter, dated Dec. 1, 1673, and giving as his authority the testimony of an eye-witness, “Henricus Arnoldi, an ingenious and veracious Dane,” Christopher Sandius wrote: “Pearl shells in Norway do breed in sweet waters; their shells are like mussels, but larger; the fish is like an oyster, it produces clusters of eggs; these, when ripe, are cast out and become like those that cast them; but sometimes it appears that one or two of these eggs stick fast to the side of the matrix, and are not voided with the rest. These are fed by the oyster against her will and they do grow, according to the length of time, into pearls of different bigness.”^[47] This possibly hit the mark with greater accuracy than the observations of the “ingenious and veracious Dane” warranted, for he seems to have had quite a different idea as to the manner in which the pearls are “fed by the oyster against her will” from those generally entertained by naturalists at the present time.

However, Oliver Goldsmith settled the matter by declaring briefly: “Whether pearls be a disease or an accident in the animal is scarce worth enquiry.”^[48] Thus it seems that notwithstanding all that had been written and the extended attention given to the subject, theory prevailed to the almost complete exclusion of practical investigation, with little intelligent advance over Topsy’s “’spect they just growed.”

Owing, doubtless, to the scarcity of pearl-bearing mollusks in their vicinities, naturalists of Europe were somewhat slow in giving attention to the origin of pearls. This is further accounted for by the fact that the gems occur more frequently in old and diseased shells than in the choice specimens which have naturally attracted the notice of conchologists.

One of the first of the original observations made on this subject was that by Rondelet, who, in 1554, advanced the idea that pearls are diseased concretions occurring in the mollusca, similar to the morbid calculi in the mammalia.^[49]

The first writer to intimate the similarity in structural material or substance between pearls and the interior of the shell in which they are formed, appears to have been Anselmus de Boot (circa 1600), who wrote that the pearls “are generated in the body of the creature of the same humour of which the shell is formed;... for whenever the little creature is ill and hath not strength enough to belch up or expel this humour which sticketh in the body, it becometh the rudiments of the pearl; to which new humour, being added and assimilated into the same nature, begets a new skin, the continued addition of which generates a pearl.”^[50] The Portuguese traveler, Pedro Teixeira (1608), stated: “I hold it for certain that pearls are born of and formed of the very matter of the shell and of nothing else. This is supported by the great resemblance of the pearl and the oyster-shell in substance and color. Further, whatever oyster contains pearls has the flesh unsound and almost rotten in the parts where the pearls are produced, and those oysters that have no pearls are sound and clean fleshed.”^[51]

Somewhat more than one hundred years later, this theory was confirmed by investigations made by the famous physicist RÉaumur (1683–1757). Microscopic examination of cross sections of pearls show that they are built up of concentric laminÆ similar, except in curvature, to those forming the nacreous portion of the shell. In a paper published by the French Academy of Science in 1717,^[52] RÉaumur noted this condition, and suggested that pearls are misplaced pieces of organized shell, and are formed from a secretion which overflows from the shell-forming organ or from a ruptured vessel connected therewith, and that the rupture or overflow is ordinarily produced by the intrusion of some foreign or irritating substance.

Sir Edwin Arnold calls attention to this theory in his beautiful lines:

In pursuance of this idea, we find, in 1761, the Swedish naturalist LinnÆus, “the father of natural history,” experimenting in the artificial production of pearls by the introduction of foreign bodies in the shell, and meeting with some degree of success. His discovery was rated so highly that it has been announced by some writers as the reason why the great naturalist received the patent of nobility, which is generally supposed to have been the reward for his services to science.

It seems that LinnÆus’s discovery but verified the old saying that there is nothing new under the sun, for later it was announced^[53] that in China—where so many inventions have originated—this idea had been put to practical account for centuries preceding, and the crafty Chinaman had succeeded in producing not only small pearly objects, but even images of Buddha, with which to awe the disciples of that deified teacher.

The method consisted in slightly opening or boring through the shell of the living mollusk and introducing against the soft body a small piece of nacre, molded metal, or other foreign matter. The irritation causes the formation of pearly layers about the foreign body, resulting, in the course of months or of years, in a pearl-like growth. While these have some value as objects of curiosity or of slight beauty, they are not choice pearls, nor for that matter were those produced by LinnÆus.

It will be observed that the theory of RÉaumur, and also that of LinnÆus, required the intrusion of some hard substance, such as a grain of sand, a particle of shell, etc., to constitute a nucleus of the pearl; and this is the accepted explanation at the present time as to the origin of many of the baroque or irregular pearls, and likewise the pearly “blisters” and excrescences attached to the shell. But not so as to the choice or gem pearls, those beautiful symmetrical objects of great luster which are usually referred to in speaking of pearls.

Examinations of many of these have failed, except in rare instances, to reveal a foreign nucleus of sand or similar inorganic substance. In searching many fresh-water mussels, Sir Everard Home frequently met with small pearls in the ovarium, and he further noticed that these, as well as oriental pearls, when split into halves, often showed a brilliant cell in the center, about equal in size to the ova of the same mollusk. From these observations, in 1826 he deduced his “abortive ova” theory, and announced:

A pearl is formed upon the external surface of an ovum, which, having been blighted, does not pass with the others into the oviduct, but remains attached to its pedicle in the ovarium, and in the following season receives a coat of nacre at the same time that the internal surface of the shell receives its annual supply. This conclusion is verified by some pearls being spherical, others having a pyramidal form, from the pedicle having received a coat of nacre as well as the ovum.^[54]

Naturalists generally accepted these conclusions, that pearls originate in pathological secretions formed, either as the result of the intrusion of hard substances, or by the encysting or covering of ova or other objects of internal origin; and there was no important cleavage of opinion until the development of the parasitic theory, as a result of the researches of the Italian naturalist Filippi, and those following his line of investigations. This theory is not severely in conflict with those of RÉaumur, LinnÆus, Home, etc., but relates principally to the identity of the irritating or stimulating substance which forms the nucleus of the pearl.

In examining a species of fresh-water mussel, the Anodonta cygnea, occurring in ponds near Turin, and especially the many small pearly formations therein, Filippi observed that these were associated with the presence of a trematode or parasitic worm, which he named Distomum duplicatum, and which appears to be closely allied to the parasite which causes the fatal “rot” or distemper in sheep. Under the microscope, the smallest and presumably the youngest of these pearls showed organic nuclei which appeared undoubtedly to be the remnants of the trematode. In Anodonta from other regions, which were not infested with the distoma, pearls were very rarely found by Filippi. In a paper,^[55] published in 1852, containing a summary of his observations, he concluded that a leading, if not the principal, cause of pearl-formation in those mussels was the parasite above noted; and in later papers^[56] he included such other forms as Atax ypsilophorus within the list of parasitic agencies which might excite the pearl-forming secretions, comparing their action to that of the formation of plant-galls.

The discovery of the parasitic origin of pearls was extended to the pearl-oysters and to other parasites by KÜchenmeister^[57] in 1856, by MÖbius^[58] in 1857, and by several other investigators. Prominent among these were E. F. Kelaart and his assistant Humbert, who, in 1859^[59] disclosed the important relation which the presence of vermean parasites bears to the origin of pearls in the Ceylon oysters. These naturalists found “in addition to the Filaria and Cercaria, three other parasitical worms infesting the viscera and other parts of the pearl-oyster. We both agree that these worms play an important part in the formation of pearls.” Dr. Kelaart likewise found eggs from the ovarium of the oyster coated with nacre and forming pearls, and also suggested that the silicious internal skeletons of microscopic diatoms might possibly permeate the mantle and become the nuclei of pearls. Unfortunately, Dr. Kelaart’s investigations were terminated by his death a few months thereafter.

In 1871, Garner ascribed the occurrence of pearls in the common English mussel (Mytilus edulis) to the presence of distomid larvÆ.^[60] Giard,^[61] and other French zoÖlogists, made similar discoveries in the case of Donax and some other bivalves. In 1901, Raphael Dubois confirmed the observations of Garner, associating the production of pearls in the edible mussels on the French coasts with the presence of larvÆ of a parasite, to which he gave the name of Distomum margaritarum, and boldly announced: “La plus belle perle n’est donc, en dÉfinitive, que le brillant sarcophage d’un ver.”^[62]

Prof. H. L. Jameson, in 1902, disclosed the relation which exists between pearls in English mussels (Mytilus) and the larvÆ of Distomum somateriÆ.^[63] The life history of this trematode, as revealed by Dr. Jameson, is especially interesting from a biological standpoint, since it is entertained by three hosts at different times: the first host is a member of the duck family; the second is the Tapes clam (Tapes decussatus), or perhaps the common cockle (Cardium edule), which incloses the first larval stage, and the third is the edible mussel, in which the second larval stage of the parasite stimulates the formation of pearls. At the Brighton Aquarium and the Fish Hatchery at Kiel, Dr. Jameson claims to have succeeded in artificially inoculating perfectly healthy mussels with these parasites by associating them with infested mollusks, and thereby producing small pearls.

From Dr. Jameson’s interesting paper we abridge the following account of the manner in which the pearls are developed. The trematode enters Mytilus edulis as a tailless cercaria, and at first may often be found between the mantle and the shell. The larvÆ, after a while, enter the connective tissue of the mantle, where they come to rest, assuming a spherical form, visible to the naked eye as little yellowish spots about one half millimeter in diameter. At first the worm occupies only a space lined by connective-tissue fibrils, but soon the tissues of the host give rise to an epithelial layer, which lines the space and ultimately becomes the pearl-sac. If the trematode larva completes its maximum possible term of life, it dies, and the tissues of the body break down to form a structureless mass which retains the form of the parasite, owing to the rigid cuticle. In this mass arise one or more centers of calcification, and the precipitation of carbonate of lime goes on until the whole larva is converted into a nodule with calcospheritic structure. The granular matter surrounding the worm, if present, also undergoes calcification. The epithelium of the sac then begins to shed a cuticle of conchiolin, and from this point the growth of the pearl probably takes place on the same lines and at the same rate as the thickening of the shell.^[64]

Fully as remarkable as the observations of Dr. Jameson are the results claimed by Professor Dubois in experimenting with a species of pearl-oyster (M. vulgaris) from the Gulf of Gabes on the coast of Tunis, where they are almost devoid of pearls, a thousand or more shells yielding on an average only one pearl. Conveying these to the coast of France in 1903, he there associated them with a species of trematode-infested mussel (Mytilus gallo-provincialis), and after a short period they became so infested that every three oysters yielded an average of two pearls.^[65] This claim has not been without criticism; but who ever knew scientists to agree?

In the pearl-oyster of the Gambier Islands (M. margaritifera cumingi), Dr. L. G. Seurat found that the origin of pearls was due to irritation caused by the embryo of a worm of the genus Tylocephalum, the life of which is completed in the eagle-ray, a fish which feeds on the pearl-oyster.^[66]

In 1903, Prof. W. A. Herdman, who, at the instance of the colonial government, and with the assistance of Mr. James Hornell, examined the pearl-oyster resources of Ceylon, announced: “We have found, as Kelaart did, that in the Ceylon pearl-oyster there are several different kinds of worms commonly occurring as parasites, and we shall, I think, be able to show that Cestodes, Trematodes, and Nematodes may all be concerned in pearl formation. Unlike the case of the European mussels, however, we find that in Ceylon the most important cause is a larval Cestode of the Tetrarhynchus form.”^[67]

In his investigation of the Placuna oyster in 1905, Mr. James Hornell found that the origin of pearls was due to minute larva of the same stage and species as that which causes the pearls in the Gulf of Manar oyster.^[68]

The spherical larvÆ of this tapeworm sometimes occur in great abundance, and there is evidence of forty having been found in a single pearl-oyster. Mr. Hornell states that the living worm does not induce pearl formation, this occurring only when death overtakes it while in certain parts of the oyster. As a consequence, pearls are more numerous in oysters which have been long infected, where the worms are older and more liable to die. This parasitic worm has been traced from the pearl-oyster to the trigger-fishes, which eat the pearl-oysters, and thence into certain large fish-eating rays, where it becomes sexually mature and produces embryos which enter the pearl-oyster and begin a new cycle of life-phases.

It seems, therefore, that the latest conclusions of science appear entirely favorable to the parasitic theory as explaining at least one, and probably the most important, of the causes for the formation of pearls; and that some truth exists in the statement that the most beautiful pearl is only the brilliant sarcophagus of a worm. This morphological change is not peculiar to mollusks, for in most animal bodies a cyst is formed about in-wandering larvÆ. Fortunately for lovers of the beautiful, in the pearl-oysters the character of the cyst-wall follows that of the interior lining of the shell, and not only simulates, but far surpasses it in luster.

While the theory that pearls are caused by the intrusion of some unusual substance has the evidence of actual demonstration in many instances, and is unquestionably true to a large extent, yet microscopic examination of some pearls suggests the theory that a foreign substance is not always essential to their formation, and that they may originate in calcareous concretions of minute size, termed “calcospherules.” As regards their origin, Professor Herdman classifies pearls into three sorts: (1) “Ampullar pearls,” which are not formed within closed sacs of the shell-secreting epithelium like the others, but lie in pockets or ampullÆ of the epidermis. The nuclei may be sand-grains or any other foreign particles introduced through breaking or perforation of the shell. (2) “Muscle pearls,” which are analogous to gallstones, formed around calcospherules at or near the insertion of the muscles. And (3) “Cyst pearls,” in which concentric layers of nacre are deposited on cysts containing parasitic worms in the connective tissue of the mantle and within the soft tissues of the body.^[69]

Even a particle of earth, clay, or mud may form the nucleus of a pearl. This was illustrated a few years ago in a fine button-shaped pearl, which was accidentally broken under normal usage and was found to consist of a hard lump of white clay surrounded by a relatively thin coating of nacre. More remarkable yet are the cases in which a minute fish, a crayfish, or the frustule of a diatom has formed the nucleus.

Several instances have been described by Woodward, Gunther, Putnam, Stearns, and others, where small fish have penetrated between the mantle and the shell of the mollusk, and the latter has resented the intrusion by covering the intruder with a pearly coating. In two or three instances the secretion occurred in so short a time that the fish suffered no appreciable decomposition, and its species is readily identified by observation through the nacreous layer. Among the remarkable specimens of this nature which have come under our observation are two very curious shells received in March, 1907, from the Mexican fisheries. One of these specimens shows an encysted fish, so quickly covered and so perfectly preserved that even the scales and small bones are in evidence; indeed, one can almost detect the gloss on the scales of the fish; and in the other—with a remarkable comet-like appearance—a piece of ribbed seaweed is apparently the object covered.

From the foregoing, it appears that the pearl is not a product of health associated with undisturbed conditions, but results from a derangement in the normal state of the mollusk. Unable to resist, to rid itself of the opposing evil, it exercises the powers given to it by a beneficent Creator and converts the pain into perfection, the grief into glory. Nature has many instances of the humble and lowly raised to high degree, but none more strikingly beautiful than this. One of the lowest of earth’s creatures, suffering a misfortune, furnishes a wonderful lesson upon the uses of pain and adversity by converting its affliction into a precious gem symbolical of all that is pure and beautiful. As written by a forgotten poet: “Forasmuch as the pearl is a product of life, which from an inward trouble and from a fault produces purity and perfection, it is preferred; for in nothing does God so much delight as in tenderness and lustre born of trouble and repentance.” As the great Persian poet Hafiz says: