384 



NATURE 



\^Feb. 



his theory in a more solid and more general way, and in this 

 case also I shall have attained my aim. L. SoHNCKE 



University of Jena 



Holothurians 



The observations which I made in 18S3 among the coral-reefs 

 of the .Solomon Group on the haliits of the Holothurians support 

 the view that these animals do not sub^^ist on living coral. I 

 carefully examined the material voided by about twenty indi- 

 viduals, and found its composition to be of a mixed character. 

 In .addition to the calcareous sand and gravel which formed its 

 bulk, there were numerous tests of the lar^je foraminifer — Orhi- 

 tolites — and several small univalve and bivalve shells, besides the 

 joints of a stony alga and the operculum of a young nerite, &c. 

 This ob-^ervation is supplementary to those contained in my 

 previous letter on this subject (Natuke, vol. xxvii. p. 7). 



Traders in this group tell me that when collecting a species 

 known in the trade as the "large tit-fish," they have frequently 

 found a small eel inside the animal, which usually escaped before 

 it could be secured. One man received a smart electric shock, 

 whilst handling a trepang containing one of these eels. 



H. B. Guppy 



H.M.S. Lark, Auckland, N.Z., January i 



Unconscious Bias in Walking 



Surely Mr. W. G. .Simpson has written from imperfect 

 memory when he tells us in Nature (vol. xxix. p. 356), " if the 

 majority of people, as Mr. Darwin argues, are left-legged, they 

 would circle to the left in a mist, as Mr. Larden says they do." 

 In Mr. l.arden's letter (p. 262) the following passage occurs: 

 "This theory {his own) involving as further consequences that 

 those in whom the left leg is the strongest would circle to the 

 right,^^ &c. ; again, " I myself am right-legged and in a mi^t I 

 always circle to the left." Although Mr. Simpson has mis- 

 quoted Mr. Larden, he has arrived at the same conclusion that I 

 did {see Nature for January 31, p. 311), but gives his views in 

 different words, namely, that " theie is a bias tmuards the 

 stronger limb, irrespective of length." John Kaf, 



The Storm of January 26 



The lowest reading, reduced to the sea-level, of the barometer 

 here, about six miles south-east of Omagh, during the gale on 

 Saturday, the 26th ult., was 2768, and occurred at 4.15 p.m. 

 Dublin time. Robert Dixon 



Clogherny, Beragh 



T 



PALESTINE EXPLORA TION 

 HE following communication has been forwarded to 

 us for publication : — 



Mediterranean Hotel, Jerusalem, January 18, 1884 

 Dear Professor Oliver, — A chest in a waterproof 

 cover leaves here to-morrow for London to Messrs. Cook 

 and Son, Ludgate Circus. It should arrive on February 

 25 or sooner, and I have directed that it should be for- 

 warded immediately to Kew. I hope to arrive soon after. 

 It contains all my dried plants. They are made up in 

 various packages, with localities written outside. Of 

 course you will have them kept dry and looked after, but 

 1 think they had better not be overhauled until I come, 

 as I should like to open them as they are, while the con- 

 tents of each package and its associations are fresh in my 

 memory. The earlier desert plants are in many cases 

 only valuable for recognition, I fear, as they are withered 

 remains, but I frequently obtained a lingering flower and 

 many seeds. All my seeds and bulbs I have sent accord- 

 ing to promise to Mr. Burbidge, of the College Botanic 

 Garden, Dublin. In the mountains about Sinai and 

 Jebel Catherine I obtained better specimens, and things 

 gradually improved to Akaba. We got through a good 

 deal of unexplored country and had a most efficient con- 

 ductor. .Along the Wady Arabah I made frequent 

 detours into the mountains on either side, and was espe- 



cially fortunate in having a good collection on Mount 

 Hor and at Petra and its neighbourhood. The flora of 

 Mount Hor (5000 feet) is extremely rich — a warm sand- 

 stone. I also collected mosses and lichens in the desert, 

 and am still gathering all I can. My collections reach 

 to here, including a run down to the Jordan. The pace 

 is now (horses) often too rapid, but the camel was an 

 admirable companion on a long march. We were delayed 

 in the Ghor-en-Safiet, at the south-east end of the Dead 

 Sea for ten days, an unparalleled sojourn in this most 

 interesting place. It was early a little, but I made large 

 collections there, and was very glad of the difficulties that 

 opposed our departure. I found many unexpected plants 

 — three ferns, for instance, on Mount Hor, and a Sta- 

 pclia. I knew the names of very few of the things, and 

 had no books, but Redhead and Lowne's papers were a 

 help, though they gave a very poor idea of the real state 

 of affairs. There is a fine ^('rt<r/« in the Ghor-en-Safiet, 

 distinct in many respects and far finer than A. seyal. It 

 is the true " scent " about which there seems a lot of 

 confusion. Hoping my collections will be satisfactory, 

 I remain yours very truly, 



(Signed) Henry Chichester Hart 



P.S. — Here in Jerusalem there are about six plants in 

 flower ; down below iir the Jordan I gathered about a 

 hundred two days ago ! (Signed) H. 



FAIRY RINGS 

 'T'HE dark green circles of grass known as "fairy 

 -»• rings" formed the subject of a paper in the Philo- 

 sophical Transactions of the new-born Royal Society in 

 1675 ; but it was only last year that the Rothamsted 

 chemists, Messrs. Lawes, Gilbert, and Warington, an- 

 nounced what IS no doubt a correct explanation of these 

 phenomena. 



The original theory of the electrical origin of the rings 

 was succeeded by that of " chemical causes " propounded 

 by Dr. Wollaston at a meeting of the Royal Society 

 in 1S07, and by Prof. Way in a paper read to the 

 British Association in 1846. Besides the "mineral 

 theory " which was here pressed into the service of a dis- 

 cussion that commenced, as already stated, more than 

 two hundred years ago, De Candolle applied his famous 

 " excretory theory " to its elucidation. At Rothamsted, 

 however, the causes of fairy rings were still regarded as 

 having been unsatisfactorily explained. 



Sir John B. Lawes and his colleague Dr. Gilbert com- 

 menced their mquiries on this subject many years ago. 

 Almost from the commencement of their experiments at 

 Rothamsted they had regarded the alternate growth of 

 fungi and grass as a striking example of what may be 

 called the " natural rotation " of crops. As long ago as 

 J 85 1 they described fairy rings in the Journal of the 

 Royal Agricultural Society as "a beautiful illustra- 

 tion of the dependence for luxuriant growth of one 

 plant upon another of different habits." It will be re- 

 membered that the experiments at Rothamsted led to the 

 substitution of what is called the "nitrogen theory" for 

 the "mineral theory " of former days, and practical agri- 

 culturists who know the value and the cost of nitrogen 

 as an all-important agent of fertility will learn, per- 

 haps without surprise, that the rich verdure of a fairy 

 ring is due to the effect of nitrogen. Nitrogen is the 

 sine quA non of plant growth, and fungi require a large 

 amount of it. From what source do they obtain it ? At 

 the present time few, if any, chemists would maintain 

 that they obtained it by the absoi ption of free nitrogen 

 from the atmosphere, but in 1S51 the eminent investigators 

 at Rothamsted attributed the nitrogen of the fungi to 

 their extraordinary power of accumulating that substance 

 from the atmosphere ; and this they thought enabled 

 them to take up the minerals which the grasses, owing to 



