224 



NATURE 



[yan. 5, 1888 



of the Benedictine monks of Fulda, the trastworthiness of the 

 lunar and solar tables, and the accuracy of the computer who 

 brought out so marvellously correct a result without knowing 

 that it agreed exactly with the true meaning of the record. 



No doubt equal credit may be given to the computer's state- 

 ment that this eclipse was total in London, totality continuing 

 at St. Paul's from ih. i6m. 20s. to ih. i8m. lor. local mean 

 time. C. S. Taylor. 



Height of T'ai Shan. 



A FORMER student of mine, Mr. S. Couling, has recently 

 ascended T'ai Shan, the loftiest of the sacred mountains of 

 China, and one of the most ancient and popular places of 

 pilgrimage. He believes that the height of it above the sur- 

 rounding plain has never before been measured, and has sent me 

 his observations to reduce. The elevation from the plain to the 

 summit comes out at 4780 feet ; whilst a temple vaguely stated 

 to be about 400 feet below the summit is, as ascertained by 

 barometer, 4485 feet above the plain. 



SiLVANUs P. Thompson. 



The Shadow of a Mist. 



Living on the Blue Mountains at an elevation of 5000 feet, 

 I am frequently astonished at the ever varying beauty of the 

 mists and clouds. But a short time ago it was my good fortune 

 to see the shadow of a mist, itself not visible. 



On the evening of November 16, shortly after 7 o'clock in 

 the evening, I was watching the electric light with which the 

 military authorities were experimenting at Port Royal, 15 miles 

 distant in a straight line. The light at times was so brilliant 

 that the shadow of a person standing 20 feet from the house was 

 distinct on the white-painted front, even when he held a lamp 

 partially turned down close to his body on the side next the 

 house. Rain was falling, but so slightly that there was no need 

 for an umbrella. No mist or cloud was visible in the direct line 

 to Port Royal, and yet a net- work of shadow was thrown on the 

 house, the meshes of which were 3 or 4 inches in width. The 

 sha,dows were all in motion, moving from east to west, in the 

 direction of the scarcely noticeable breeze ; individual portions 

 of the meshes disappearing and re-forming as they moved, so that 

 it was quite dazzling to look at the shadow, reminding me of 

 the ripple on water as seen against a strong light. A puff of 

 tobacco smoke had a shadow only when an inch or two from the 

 house, so that the mist must have been much denser, and yet it 

 cannot have been of any trreat breadth, or the shadow would have 

 been uniform instead of reticulated. No doubt many of your 

 readers can explain this appearance, which to me seemed so 

 singular. W. Fawcett, 



Director of Public Gardens and Plantations. 



Cinchona, Gordon Town P.O., Jamaica, December i, 1887. 



The Ffynnon Beuno and Cae Gwyn Caves. 



It would seem that so long as the controversy with regard to 

 the contents of these caves is confined to Dr. Hicks, Prof. 

 Hughes, and Mr. W. G. Smith, the points at issue will never be 

 decided. Dr. Hicks argues most needlessly for the /r^'-Glacial 

 age of the cave deposits ; Prof. Hughes calmly assumes that the 

 outside deposits are posl-GX^disX ; and many geologists must be 

 heartily tired of hearing these two gentlemen contradict one 

 another without defining what they mean by the terms Glacial 

 and post-Glacial. 



The fact is that the St. Asaph drift (to which Prof. Hughes 

 now admits the outside deposits belong) is part of the later 

 Glacial series of Northern England ; and Prof. Hughes has no 

 right to call it post-Glacial without defining what he means by 

 that term. Most people call them Glacial deposits. If there- 

 fore the cave-deposits are older than this drift, they are not 

 necessarily /;v- Glacial, as Dr. Hicks maintains, but only anterior 

 to what Mr. Mellard Reade terms the marine low-level boulder- 

 clays. Now many think that these clays and their associated 

 sands are coseval with, or newer than, the so-called post-Glacial 

 river-gravels of Southern England. It is not surprising there- 

 fore that the cave fauna should be the same as that of the river- 

 gravels, and it is perfectly needless to compare it with the fauna 

 of the Cromer Forest bed. 



In Lincolnshire the same marine shells occur in sands and 

 gravels beneath the latest sheet of boulder-clay, and a gravel 



beneath the same clay at Burgh has yielded teeth and bones of 

 Elephas antiquus. Rhinoceros leptorhinus, and Bos primigenius. 

 These beds are on the same line of latitude as St. Asaph, »and 

 are probably of the same age as that drift ; but it may be that 

 neither of them are older than the oldest river-gravels of the 

 Cam or Thames valleys. 



It has been repeatedly pointed out that the terms Glacial 

 and post-Glacial cannot be used as conveying any idea of relative 

 ,ige except along one and the same parallel of latitude, and it is 

 rather surprising that the Woodwardiaa Professor of Geology 

 should seem to be unaware of this. If by post-Glacial Prof. 

 Hughes means later Glacial or newer Pleistocene, everyone will 

 probably agree with him, but he confuses the issue by his bad 

 choice of terms. 



The palaeontological evidence is really of no value — the argu- 

 ment leads nowhere ; what we want is an expression of opinion 

 by some geologist who has seen the locality and the recent ex- 

 cavations, regarding the explanation proposed by Prof. Hughes, 

 viz. that the present position of the bones beneath the marine 

 drift is due to the falling in of the roof of the cave near one 

 entrance, while the animals may have got into the cave by 

 another opening. Many geologists have visited the locality — 

 will some of them communicate their views on this point ? 



A. J. Jukes Browne. 



Southampton, Decejober 28, 1887. 



THE OLD MOUTH AND THE NEW: A STUDY 

 IN VERTEBRATE MORPHOLOGY. 



" 'X*HE question of the nature of the mouth," says 

 •■• Prof. Dohrn in one of the first of his celebrated 

 " Studien zur Urgeschichte," "is the point about which 

 the whole morphological problem of the Vertebrate 

 body revolves." According to Dohrn, the present mouth 

 of Vertebrates arose from the coalescence of a pair of 

 gill-clefts. In this we have an example of Dohrn's 

 principle of change of function, and also, as I hope 60on 

 to demonstrate, of Kleinenberg's law of the substitution 

 of organs. I do not now wish or intend to give an 

 account of the researches by which Dohrn showed that 

 the mouth in some cases first arises as a pair of lateral 

 invaginations of epiblast, still less of my own small con- 

 tribution to this question, which consisted in recording 

 the facts that the mouth also resembles a gill-cleft in 

 some other particulars. 



It suffices here to say that these researches have not 

 yet been refuted, and that the view that the present mouth 

 of Vertebrates is, so to speak, a new structure, rests on a 

 very sound foundation. 



With the blastopore as the foundation of mouth and 

 anus I have here no concern, nor have I any sort of 

 sympathy with the upholders of a theory which has 

 been condemned and rejected by embryologists such as 

 Lankester, Kleinenberg, and Salensky. 



The problem I have to discuss is, granted that the 

 present Vertebrate mouth is a new ^ structure, what traces, 

 if any, are to be found of the old mouth t It is conceiv- 

 able, and I strongly emphasize the point, that the old 

 mouth might have disappeared, even from the develop- 

 ment, without leaving a trace behind. 



We seem to be gradually getting out of the idea that 

 ontogeny is even a fair repetition, much less a perfect 

 one, of phylogeny, for absolutely rudimentary organs 

 (organs performing no function at all) are only retained 

 as larval or embryonic organs, as the basis or Anlagc 

 of other organs, or, finally, because they are insepar- 

 ably connected with the development of other organs. 

 Of the latter a fair case, it seems to me, is to be 

 seen in the rudiment of the parietal eye in the higher 

 Vertebrates. This organ, functionless except in a few 

 fishes and reptiles, possibly only reappears in the develop- 

 ment because it is intimately connected in some way or 

 other with the paired eyes. 



A still better example is, I think, to be met with in the 



' It is rather paradoxical to speak of a thing as new which has existed in 

 its present form for untold millions ot yeais. 



