November 2, 1905] 



NA TURE 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opinions 

 expressed by Ins correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for tliis or any other part of Nature. 

 No notice is taken of anonymous communications.] 



Remarkable Coelenterata from the West Coast of 

 Ireland. 



I have been allowed to examine a small collection of 

 Alcyonaria and Antipatharia that has been obtained M the 

 fisheries branch of the Department of Agriculture for 

 Ireland from deep water off the west coast of Ireland, and 

 as this reveals some features of special interest I should 

 be glad of an opportunity to write a short preliminary 

 note upon it pending the examination of the species in 

 detail. 



The most interesting feature, perhaps, is the Coralhid, 

 Pleurocorallium johnsoni, from 3S2 fathoms, about sixty 

 miles off Achill Island. The family of precious corals to 

 which this species belongs has hitherto only been obtained 

 in the Mediterranean Sea, the Japanese seas, off Madeira 

 and the Cape Verde islands, and in the Banda Sea. The 

 specimens obtained by the Challenger in the Banda Sea 

 were "dead," but I have recently published a preliminary 

 note on a new species of precious coral from deep water 

 off the coast of Timor, which was captured " alive " by 

 the naturalists of the Siboga Expedition. 



The distinction between the genus Corallium, to which 

 C. nobile, the precious coral of the Mediterranean, 

 C. japonicum, and C. reginae. the new species from 

 Timor, belong, and the genus Pleurocorallium is not a 

 distinction of very great importance, and, as recently 

 pointed out by Kishinouye, cannot, with convenience, be 

 much longer maintained. If, however, for the present we 

 retain the two generic names it must be noted that 

 Corallium no longer maintains its monopoly of corals that 

 are precious, as the species Pleurocorallium elatius yields 

 some of the most valuable classes of coral obtained in the 

 Japanese fishery. Both in Japanese waters and off the 

 Cape Verde Islands the valuable and the commercially 

 worthless Coralliida; occur in the same fishing area, and 

 consequently it would not be a matter for surprise if a 

 renewed investigation of the locality from which the Irish 

 Fishery Department obtained its specimen of Pleuro- 

 corallium johnsoni yielded some specimens of commercial 

 value. 



I should not like to suggest the prospect of a coral 

 fishery off the coast of Ireland, as the sea is too stormy 

 and the water too deep at the station from which the 

 specimen came to render any such fishery commercially 

 successful, but it would be a matter of considerable 

 scientific interest to find that precious corals are growing 

 within a few miles of our British coasts. 



The second feature of interest is the occurrence in these 

 waters of at least three species of Antipatharia. This 

 group of Coelenterata is one which I thought was entirely 

 exotic. I can find no mention of any Antipathsrians in 

 any of the lists of the British marine fauna that I have 

 examined, but perhaps some of your readers could inform 

 me if I have overlooked any references to them. The 

 species are, I believe, Cirrhipathes spiralis, Antipathella 

 gracilis, and a species which I think must be new, but is 

 allied to Stichopathes liitkeni in some respects. 



Among the other interesting things in the collection 

 are representatives of the alcyonarian genera Ceratoisis, 

 Stachyodes, and Eunephthya, which I believe are new 

 to the British fauna. The two pennatulid genera 

 Kophobelemnon and Umbellula were obtained in deep 

 water off the west coast of Scotland by the Knight Errant 

 (Kophobelemnon only) in 1880, and by the Triton in 1882. 

 These also have now been found off the west coast of 

 Ireland. Although these genera may now be included in 

 the British fauna as being found within the British area 

 as defined by the British Association committee of 1888, 

 they really represent the fauna that is common to the 

 " mud line" of Murray of the eastern side of the North 

 Atlantic Ocean. 



Thus Pleurocorallium occurs off the Cape Verde Islands, 

 Stachyodes off the Azores, Ceratoisis grayii off the coast 



NO. 1879, VOL. 73] 



of Portugal, Antipathella gracilis off the coast of Madeira,. 

 Kophobelemnon and Umbellula off the west coast of Scot- 

 land. These genera, with many others that live with 

 them, constitute a fauna which is quite distinct from the 

 ordinary shallow-water fauna of the British area. 



1 J. HlCKSON. 



Victoria University of Manchester, October 24. 



Action of Radium on Gelatin Media. 



Some misapprehension appears to exist in certain 

 quarters as to the precise nature of the bodies I have 

 called radiobes, as distinct from such aggregations as 

 those which M. Dubois has obtained by the action of the 

 salts of barium, radium, and manganese upon bouillon. 

 M. Dubois describes his bodies as "grosses vacuolides," 

 and their appearance is quite different from that of the 

 bodies I have described, judging by the drawings which 

 have been reproduced in the Revue des Idies during the 

 last few months. 



I have observed two distinct types of bodies, of an 

 entirely different order of magnitude, one type, radiobes, 

 extremely minute and only visible with the highest powers : 

 the other visible with an ordinary magnifying glass. The 

 latter are decidedly crystalline in their structure, and 

 resemble the bodies obtained in various ways by the action 

 of salts on gelatin. They are like the ones described by 

 Schenck, and very like those obtained by Dubois and 

 others. 



The smaller type cannot be said to be large in any 

 sense of the word, and are like the minutest visible diplo- 

 cocci or biscuit-shaped cocci. They do not exceed this size 

 to any great extent. 



It is therefore desirable that the two types should not 

 be identified, as their appearance, order of magnitude, 

 structure and behaviour seem to be quite different. 



M. Dubois has not noticed these, and therefore it 

 seems to me that his claim to priority is quite irrelevant. 



Cambridge, October 21. John Butler Burke. 



Border occasionally seen between Light and Dark 

 Regions on Photographic Prints. 



I have once or twice been asked why photographs are- 

 apt to show a line or band or edging along the boundary 

 of a bright and dark region. My assistant, Mr. E. E. 

 Robinson, has thought of the reason, and it may be con- 

 venient to publish it. In a developed film the exposed 

 portion perceptibly differs in thickness from the unacted-on 

 portion, and accordingly the linear boundary of two con- 

 trasted regions may sometimes act as a cylindrical lens, 

 and during printing either concentrate or disperse the light 

 on the positive immediately beneath it. 



October 20. Oliver Lodge. 



Terminology in Electro-physiology. 



I would deem it a favour to be assigned the space of 

 a letter in order to make a suggestion in connection with 

 the above still vexed subject. 



It cannot be said that even now all is peace in the 

 realm of electrical terminology as applied to physiological 

 phenomena, in spite of Dr. Waller's helpful efforts in this 

 direction. Dr. Waller's term " zincative " admirably 

 expresses that a given region (a) of excited tissue is 

 "electromotive like the zinc of a voltaic couple," 1 is, in 

 fact, a source of current towards a region (e) of less excited 

 or non-excited tissue (the current, 

 of course, travelling in the tissue 

 from the region a to the region 

 B, and in the external circuit 

 from the region b to the region 

 \); but it leaves untouched the 

 solution of the old muddle over 

 the use of the signs + and — . 



Confessedly, " zincative " avoids any reference to + 

 and -, but every teacher of physiology knows that sooner 

 or later the + and — must appear, and with them all 

 the ambiguities of " negativity of action, "_ &c, if the 

 student is to make his notes " agree " with his text-book. 

 1 " 1 he Signs of Life from their Electrical Aspect," p. 17. (Murray, 190a 



