Oct. 21, 1880] 



NATURE 



583 



LETTERS TO THE EDITOR 



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 by his correspondents. Neither can he undertake to return, or 

 to correspond with the writers of, rejected vianiiscripis. No 

 notice is taken of anonymous communications.] 



[ The Editor urgently requests correspondents to keep their letters as 

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 munications containing interesting and novel facts.] 



Photograph of the Nebula in Orion 

 During the night of September 30 I succeeded in photo- 

 graphing the bright pari of the nebula in Orion in the vicinity of 

 the trapezium. The photographs s-how the mottled appearance 

 of this region distinctly. I intend shortly to publish a detailed 

 description of the negatives. They were taken by the aid of a 

 triple objective of j eleven inches aperture made by Alvan Clark 

 and Sons, and corrected especially for the photographic rays. 

 The equatorial stand and driving-clock I constructed myself. 

 The exposure was fifty minutes. Henry Dr.\per 



New York, October 2 



An Annelidan Entozoon 



While examining the intestinal tract of Megaderma frons from 

 the Gold Coast, I found coiled up spirally and adhering to the 

 wall of the lower part of the ileum a small parasite about half an 

 inch in length. On placing this under the microscope I was 

 much surprised to find that it belonged to a class of worms (An- 

 nelida), none of the species of which have hitherto been known 

 as Entozoa, and further that I was unable to refer it to any of 

 the orders of that class. 



On showing it to Dr. J. D. Macdonald, F.R.S., he quite 

 agreed with my opinion that it represents a new order of Anne- 

 lids, and is moreover disposed to consider it as a connecting- 

 link, hitherto wanting, between the Chcetopoda and the true 

 leeches. 



The specimen in question is about half an inch in length with- 

 out distinct segmentation, except what is indicated by the per- 

 fectly regular disposition of the cephalo-somatic appendages — 

 seventy-three pairs, extending from the anterior almost to the 

 posterior extremity of the body — whereof those occupying the 

 anterior attenuated fourth of the body are fin-like lamellae, 

 apparently branchial, with a single unarmed mouth not provided 

 with a proboscis, with the intestine spirally coiled round the 

 ovarian tube and terminating inferiorly at the posterior extremity 

 of the body. 



Megaderma frons, the host of this remarkable annelid, is a 

 species of bat of very peculiar aspect, which is apparently 

 widely distributed throughout and restricted to the tropical parts 

 of the Ethiopian region. It belongs to a genus whereof one of 

 the species at least is known to suck the blood of smaller bats, 

 which it captures on the wing (see my " Monograph of the 

 Asiatic Chiroptera," p. 77), and as all the species closely re- 

 semble one another in structure, it is exceedingly probable that 

 they have all much the same habits. 



Although I found remains of insects in the intestinal canal of 

 the specimen from which the above-noticed parasite was taken, 

 yet there was also mixed up with them a large quantity of hair, 

 not from its own body, but evidently (judging from its micro- 

 scopic structure) that of some other bat on which very likely it 

 had been feeding. It is also worthy of notice that the intestine 

 of the parasite is filled with a reddish matter like the remains 

 of blood. 



I have handed over this very interesting specimen to Dr. 

 Macdonald, who will shortly publish a fuU description of it with 

 figures. G. E. DoBSON 



Royal Victoria Hospital, Netley, October 7 



Sounds made by Ants 



From the very interesting remarks lately made by Sir John 

 Lubbock regarding the habits and capabilities of ants, I gather that 

 he seems to consider them as a silent group. The modes of pro- 

 ducing sounds among insects are as various as beautiful, whether 

 by internal or external agency. As a rule the larger animals 

 produce sound by internal means, i.e. voice, and insects by some 

 external means. 



Among ants I know of two varieties or distinct kinds, a black 

 and brown, that make a concerted noise loud enough to be heard 



by a human being at twenty or thirty feet distance, and which 

 sound is produced by each ant scraping the horny apex of the 

 abdomen three times in rapid succession on the dry crisp leaves 

 of which the nest is usually composed. 



The noise made by a single ant is sufficiently loud to be heard 

 on a very dry leaf if attention is directed to it, and no doubt by 

 this means of a vibrating medium they can without special audi- 

 tory organs communicate \\'ith each other. I had the honour of 

 first discovering that the great Mygale stridulans made a noise ; 

 the apparatus by which it was produced was discovered and fully 

 described by Mr. J. Wood Mason of the Indian Museum, and 

 I should be glad if I am the means of making a similar dis- 

 covery regarding ants. White ants (so-called) make a noise 

 which is audible — if put on crisp paper — by suddenly shaking 

 the whole body, and seem to warn each other by this means. 



Sapakati, Sibsagor, Asam, August 20 S. E. Peal 



Faraday Exhibiting Ghosts 



Mr. J. INNES Rogers' communication on a " Spectre of the 

 Brocken at home " reminds me of a passage in Dr. Bence Jones's 

 "Memoir of Faraday," vol. i. p. 422. 



Faraday's niece, Miss Reid, thus writes: "One evening a 

 thick white mist rose and completely hid everything before us. 

 About ten o'clock my uncle called me into his room to see a 

 spectre. He placed the candle behind us as we stood at the 

 window, and there, opposite to us, appeared two gigantic 

 shadowy beings, who imitated every movement that we made." 



Ardchapel, N.B., October 16 W. S. 



Ice under Pressure 



In reply to C. A . M.'s letter of last week I would make the fol- 

 lowing remarks : — Ice is not an exceptional substance, for mercuric 

 chloride has also given experimentally the same results, and 

 though I have not yet had the opportunity of submitting other 

 substances to the same conditions, yet I conclude from other 

 experiments that all the bodies which I have so far investigated, 

 and which are of the most varied description, will also exhibit 

 the same phenomenon. As I have not yet published my detailed 

 results, I do not wish at present to enter more fully into the 

 subject, but I may say that the influence of pressure in the 

 present case is not of the same kind as that referred to by 

 C. A. M. as occurring in the text-book named, for the following 

 amongst other reasons. From Prof. Thompson's prediction 

 and Sir Wm. Thomson's experiments it resulted that the 

 melting-point of ice is lowered by pressure, and lowered in 

 proportion to the pressure, whereas in my experiments, at any 

 rate so far as I have at present seen, we do not vary the melting- 

 point by diminishing the pressure, but we prevent the substance 

 from melting at all. If the pressure be increased everi but 

 slightly above the critical pressure, the ice melts at its ordinary 

 melting-point. The influence of pressure in this case is not one 

 of degree varying with the amount by which the pressure is 

 reduced. The two cases are, I consider, entirely different, and 

 are not contradictions. Similar remarks would probably apply 

 to paraffin and spermaceti, though these are bodies which have 

 not come within the range of my experiments. 



Firth College, Sheffield, October 6 Thos. Carnelley 



A Peat Bed in the Drift at Oldham 



In Nature, vol. xxii. p. 460, there is a letter by Mr. Jas. 

 Nield, giving an interesting description cf unique, or nearly 

 unique, appearances in the boulder clay near Oldham. It 

 appears that this glacial deposit has one or more beds of 

 peat, or fragments of peat, intercalated along with it at 

 various depths, leading to the inference that the clay had 

 been stirred up and the fragments of peat had in some 

 manner been mixed with it. That peat bogs, or surface 

 black peaty mould, had existed at no great distance is a 

 conclusion forced upon us, and that the action of ice and snow, 

 probably during a submergence, had mashed up the clay and dis- 

 tributed the peat amongst it. The boulder clay, and the scratched 

 mountain sides, and the travelled fragments of rock, do not 

 extend over the whole of England. It used to be said by 

 geologists that the effects of a severe Arctic climate could not be 

 detected south of a line drawn across the country from London 

 to Bristol ; by which it was infen'ed that all the land north of 

 that line had been under water, subject to the influences of snow 



