June J 6, 1887] 



NATURE 



157 



that should illustrate the events in families, schools, 

 houses, &c., such as the stained-glass windows in 

 churches do those in the history of the Bible, How 

 prettily girls might design pictographs to record notable 

 events in a pleasant tour, and interchange them with 

 their fellow-travellers as presents. Such designs as these 

 could be made subjects of embroidery, or, if on a larger 

 scale, of that brass repousse work which is, or was, so 

 much in fashion. It would be by no means difficult to 

 convert them into actual medallions. First the wax model, 

 then the plaster cast, then the cast in white fusible metal, 

 then the covering with an electrotyped coating of silver, 

 just in the way that the ancient coins are reproduced at 

 the British Museum, at the cost of about three shillings 

 each, which are now so frequently used in rows for 

 necklaces. What a delightful memorial of twenty-five years 

 of wedded history might be given by a husband to his 

 wife, in the form of a necklace of such medals. It would 

 be a pleasant labour to make a set of designs, which an 

 artist could afterwards put into better forms, and construct 

 from them the wax medallions for the electrotypist to cast 

 and turn into metal. I commend this idea of commemora- 

 tive pictographs and glyptographs (as works in relief 

 ought to be called) to the notice of amateur artists, 

 whether they work in pencil, ink, colour, carving, em- 

 broidery, repousse work, china painting, or in modelling. 

 This volume is an excellent example of the growing 

 variety and wealth of material now available to inquirers 

 into the origin of language. We meet in it with abundant 

 evidence of the rapidity with which pictographs become 

 abbreviated into conventional symbols, and are thereby 

 adapted to play the same important part in reasoning 

 that is usually played by words. I cannot see that it 

 makes any fundamental difference in the use of symbols 

 whether they appeal to the ear or to the eye, though I 

 fully grant that on many grounds, not worth entering 

 into here, the former is more generally convenient, and 

 best suits the idiosyncracies of the majority of persons. 

 The unassisted sense of touch, as we have learnt from 

 the case of Laura Bridgeman, may afford an adequate 

 basis for the exercise of a considerable amount of reason- 

 ing. And for aught I can see to the contrary, a dog who 

 " ponders," to use a dog-trainer's expression, may occa- 

 sionally be carrying out some real act of thought by the 

 aid of imagined and symbolic odours. 



Francis Galton. 



COCOA-NUT PEARLS. 



'T^ HE following letter has been sent to us by Dr. Sydney 

 -*■ J. Hickson : — 



" During my recent travels in North Celebes I was 

 frequently asked by the Dutch planters, and others, if I 

 had ever seen a ' cocoa-nut stone.' These stones are said 

 to be very rarely found (i in 2000 or more) in the peri- 

 sperm of the cocoa-nut, and when found are kept by the 

 natives as a charm against disease and evil spirits. 

 This story of the cocoa-nut stone was so constantly told 

 me, and in every case without any variation in its de- 

 tails, that I made every effort before leaving to obtain some 

 specimens, and eventually succeeded in obtaining two. 



"One of these is nearly a perfect sphere, 14 mm. in 

 diameter, and the other, rather smaller in size, is irregularly 

 pear-shaped. In both specimens the surface is worn 

 nearly smooth by friction. The spherical one I have, 

 had cut into two halves, but I can find no concentric or 

 other markings on the polished cut surfaces. 



" Dr. Kimmins has kindly submitted one half to a care- 

 ful chemical analysis, and finds that it consists of pure 

 carbonate of lime without any trace of other salts or 

 vegetable tissue. 



" I should be very glad if any of your readers could 



inform me if there are any of these stones in any of the 

 Museums, or if there is any evidence beyond mere hearsay 

 for their existence in the perisperm of the cocoa-nut." 



On this letter Mr. Thiselton Dyer, to whom we sent it, 

 has been good enough to make the following remarks : — 



Dr. Hickson's account of the calcareous concretions 

 occasionally found in the central hollow (filled with fluid — 

 the so called " milk ") of the endosperm of the seed of the 

 cocoa-nut is extremely interesting. It appears to me a 

 phenomenon of the same order as tabasheer, to which I 

 recently drew attention in this journal. 



The circumstances of the occurrence of these stones or 

 "pearls" are in many respects parallel to those which 

 attend the formation of tabasheer, In both cases, mineral 

 matter in palpable masses is withdrawn from solution in 

 considerable volumes of fluid contained in tolerably large 

 cavities in living plants — and in both instances they are 

 Monocotyledons. 



In the case of the cocoa-nut pearls the material is 

 calcium carbonate, and this is well known to concrete in 

 a peculiar manner from solutions in which organic matter 

 is also present. 



In my note on tabasheer I referred to the re- 

 ported occurrence of mineral concretions in the wood 

 of various tropical Dicotyledonous trees. Tabasheer is 

 too well known to be pooh-poohed ; but some of my 

 scientific friends expressed a polite incredulity as to the 

 other cases. I learn, however, from Prof Judd, F.R.S., 

 that he has obtained a specimen of apatite found in cutting 

 up a mass of teak-wood. The occurrence of this mineral 

 under these circumstances has long been recorded ; but 

 I have never had the good fortune to see a specimen. 



Returning to cocoa-nut pearls, I send you a note 

 which the Tropical Agriculturist for April last quotes 

 from the Straits Times: — 



" A trade journal appearing in Java gives the following 

 particulars regarding a peculiar kind of pearl found in 

 this part of the world : — It is well known that pearls 

 have been met with within oysters and mussels. Some- 

 times even trees yield pearls. In the Proceedings of the 

 Boston Society of Natural History, there is a paper by Mr. 

 J. Bacon regarding the kind of pearls often found within 

 cocoa-nuts. The specimens shown have been bought at 

 Singapore. They are said to be so rare in the East Indies 

 as to be highly prized by the native rajahs, and worn by 

 them as precious stones. Mr. Bacon himself possessed a 

 small pearl of this sort. It is said that when allowed to 

 grow, they will reach the size of cherries. This pearl 

 resembles the common variety in smoothness, whiteness, 

 and scant lustre of surface. It is harder than it, and 

 almost as hard as feldspar or opal. The common pearl 

 varies in hardness, but is never harder than feldspar. The 

 cocoa-nut pearl consists of carbonate of lime, with very 

 few organic substances remaining after treatment with 

 acid solutions. This organic matter is insoluble, shows 

 no trace of vegetable substances after microscopical 

 examination, and seems to be akin to albumen in structure. 

 In the common pearl there is also found an albuminous 

 substance, but the latter remains unchanged in appear- 

 ance and lustre even after the calcareous constituent parts 

 have been dissolved away. In other respects microscopical 

 research has brought out the fact that the cocoa-nut 

 pearl is formed of concentric layers without any nucleus. 

 The whole mass is made up of layers of fine crystalline 

 fibres. Prof Bleekrode, in commenting on the former 

 in a Dutch scientific periodical, says that Rumphius, the 

 famous botanist, had in his'HerbariumAmboinense,'given 

 full particulars of this petrifaction in the cocoa-nut. 

 Rumphius has even illustrated his account of it by 

 accompanying drawings of the two forms in which this 

 kind of pearl is met with — pear-shaped and round, either 

 of uniform appearance or vvith red edges. Hardly one 



