468 



KNOWLEDGE. 



December, 1913. 



passes easily and the effects at higher pressures obtained with 

 air are due to the presence of oxygen, the negative discharge 

 in nitrogen being very difficult to obtain at high pressures. 

 In hydrogen (he discharge merely amounts to a glow round 

 the terminal. The positive discharges, when the positive 

 electrode is put against the sensitive side of the plate, are not 

 so distinctly different in different gases, and they merely 

 become finer at higher pressures. These experiments will 

 help to define many curious effects obtained in the brush and 

 spark discharge, but there is much which remains to be 

 cleared up. The actual condition of affairs at the negative 

 electrode is, perhaps, one of the most interesting points upon 

 which the above researches may throw some light. 



ZOOLOGY. 



By Professor J. Arthur Thomson, M.A., LL.D. 



COMMENSAL CRUSTACEANS IN CHAETOPTERUS 

 TUBES. — Professor A. S. Pearse has studied three 

 Crustaceans — Polyonyx macrocheles, Pinnixa chaeto- 

 pterana, and Pinnotheres maculatus — which occur as com- 

 mensals in the tubes of Chaetopterus variopedatus at 

 Wood's Hole. The two first-named are not closely related, 

 Polyonyx being a Galatheid and Pinnixa a true crab of 

 the family of Pinnotherids, but they have many similarities. 

 Like most Crustaceans, they are strongly thigmotropic, and 

 creep into crevices or tubes, which would easily account for 

 their taking up their abode with Chaetopterus. They are 

 rarely found elsewhere. They become quiet when a shadow 

 passes over them, which has probably protective value. They 

 feed by " net casting," after the manner of barnacles, and this 

 is admirably suited for the capture of food within the tubes. 

 The " nets " in both are formed by the inner blades (or 

 endopodites) of the third maxillipede, which are well supplied 

 with plumose setae and are swept through the water. Both 

 forms have the last leg shortened. Both have a long breeding 

 season, producing one brood after another, and this is perhaps 

 fostered by the sheltered life. They gain from their 

 association with the worm, but the worm's view of the 

 situation is unknown. 



REMARKABLE BLIND CEPHALOPODS.— One of the 

 most precious spoils of the Michael Sars North Atlantic Deep 

 Sea Expedition of 1910 (carried out under the auspices of the 

 Norwegian Government and the superintendence of Sir John 

 Murray and Dr. Johan Hjort) was a blind cuttlefish, Cirro- 

 thauma murrayi n. g. et sp. apparently adapted for deep sea 



life. Three thousand metres of wire were out when it was 

 captured. The specimen is perfectly gelatinous and semi- 

 transparent. Its fragility recalls that of a Ctenophore. A 

 delicate web unites the arms. The nerves can be seen 

 shining through the whole length of the arms. The gelatinous 

 body exhibits an exceedingly faint violet colour, and only the 

 parts round the mouth, the proximal portions of the arms, 

 and the web exhibit the purple chocolate colour peculiar to 

 many deep-sea animals. Chromatophores are absent, except 

 a rhombic one between the two fins. Very peculiar minute 

 suckers (thirty-six in number) poised on long spindle-shaped 

 and clumsy stalks of gelatinous substance occur on the inner 

 side of the arms. They are evidently out of function, being 

 flattened and without a sucking pit, and smaller than the normal 

 proximal suckers. In each stalk there is a curious structure 

 which may be a luminescent organ and reflector. The eye is 

 minute, without a lens, with a very degenerate retina and 

 optic nerve. There are deep-sea cuttlefishes with small eyes, 

 but no case save this one is known where the structure of the 

 eye is involved. Its degeneration has gone further than in 

 many blind vertebrates. 



PHOSPHORESCENCE OF PEN NATU LIDS.— Professor 

 W. A. Herdman has recently described the "phosphorescence" 

 of Funiculina quadrani<ularis,the\a.rgest British Pennatulid. 

 The light on the bare part of the colony was more intense 

 that that produced by the polyps. " The long bare lower 

 part of the stem, nine inches to a foot in length, when gently 

 stroked in the dark glows with a continuous sheet of light 

 of (it seems to me) a pale green colour which flickers or 

 pulsates like a lambent flame." In Pennatula phosphorea 

 the luminosity seems to be confined to the polyps. It is 

 more general and more lasting than the sparkles that the 

 polyps give in Funiculina. In the report on the spoils of 

 the Michael Sars Expedition, the artist has given a figure of 

 the luminescence of Umbellula giintheri which was still 

 brilliantly phosphorescent although drawn up from the 

 immense depth of more than five thousand metres. Dr. 

 Hjalmar Broch refers to Sir Wyville Thomson's note that 

 the spectrum of Pennatulid phosphorescence is very restricted 

 and sharply included between b and D. Niedermeyer found 

 that the phosphorescence of Pteroeides griseum was 

 restricted to the polyps and small zooids, and is temporarily 

 lost after exposure to sunshine, which probably destroys, for 

 the time being, the product of some intracellular secretion. 

 Although its phosphorescence is only seen by us when we 

 stimulate these Pennatulids, Broch suggests that deep-sea 

 forms may show it without irritation. 



NOTICES. 



CHANGE OF ADDRESS.— We are asked to announce 

 that Messrs. Haseltine, Lake & Company, Patent Agents, 

 have removed from 7 and 8, to No. 28, Southampton Build- 

 ings, Chancery Lane, E.G. 



OPTICAL LANTERNS.— Messrs. Newton & Company's 

 new catalogue is noteworthy for the many types of science 

 lanterns listed, and is particularly valuable on account of the 

 variety of arc lamps and other projection illuminants therein 

 described. 



SCIENTIFIC BOOKS.— We have received from Mr. H. K. 

 Lewis his quarterly list of new books added to the circulating 

 library. It contains the books published from July to Sep- 

 tember. Under the heading, " Technology," we notice that 

 the first volume of the new edition of Lewkowitsch's 

 "Chemical Technology and Analysis of Oils, Fats, and 

 Waxes " is included. 



THE "WELLCOME" PHOTOGRAPHIC RECORD 

 AND DIARY, 1914.— This useful little pocket guide to 

 photography has been reissued by Messrs. Burroughs, 

 Wellcome & Company. Particular attention is given in 

 this edition to blue and green toning and the production of 

 various colours by development. It should find a place in 

 every photographer's library. 



SCIENTIFIC, INDUSTRIAL AND TECHNICAL 

 BOOKS. — Messrs. Crosby, Lockwood & Son have published 

 a new illustrated catalogue of books coming under the above 

 heading, and we are asked to announce that they will be 

 willing to send a copy post free to all who may be in any way 

 interested. 



SECOND-HAND MICROSCOPES.— Messrs. H. F. Angus 

 and Company have issued their fourth catalogue under this 

 title. A good selection of instruments, objectives, and 

 accessories, as well as general optical and physical apparatus, 

 will be found therein. 



NATURAL HISTORY BOOKS.— In Messrs. John 

 Wheldon & Company's latest catalogue will be found, 

 besides general literature, a list of important remainders of 

 books on Natural History, and many sets of scientific 

 journals, both English and foreign. 



THE SCIENTIST'S REFERENCE BOOK AND 

 DIARY, 1914. — Once again we have pleasure in noting the 

 appearance of this handy pocket book. In addition to a diary 

 and space for memoranda it contains tables useful for 

 everyday reference and a short account of the progress of 

 science in 1913. It is published by Messrs. James Woolley, 

 Sons & Company, Limited, of Manchester. 



