\Nov. 2, 1876] 



NATURE 



[introduction of cultivation in the neighbourhood of the Great 

 ! Salt Lake of North America has increased the rainfall, and 

 j caused the level of the lake to rise. Joseph John Murphy 



Antedon rosaceus (Comatula rosacea) 

 The communication from Major Fred. H. Lang in Nature, 

 irol. xiv. p. 527, as to the abundant capture of Comatula rosacea 

 In Torbay by himself and Mr. Hunt with the dredge during last 

 lonth, is a valuable contribution to the study of the question of 

 jthe appearance and disappearance o^ certain marine animals in 

 certain localities respecting which we know so little. It is 

 specially interesting to the Birmingham Natural History and 

 Microscopical Society, and as president of the Society and 

 reporter during the marine excursion to Teignmouth in 1873, 

 alluded to by Major Lang, I must i \.y that I read it with very great 

 surprise and pleasure. My knowledge of the locality has ex- 

 tended over a period of about thirteen years, and during that 

 time I have on several occasions dredged the ground which he 

 mentions, and never once succeeded in taking an adult specimen 

 of the rosy feather star, much less the more interesting peduncu- 

 late form of it. I have not, however, dredged there since our 

 marine excursion. Mr. Gosse, whose experience is very large, 

 and who resides in the neighbourhood, to whom I showed our 

 mounted specimens, had never befere seen the animal in that 

 form, and there is no mention made of the adult animal in any 

 of his descriptive works except in "A Year at the Shore," 

 where at p. 1 82 he states, " We sometimes but very rarely find 



on this coast a very lovely form of this class of animals 



Comatula rosacea, a fine specimen of which, taken by myself in a 

 little cove near Torquay, I have delineated." This was written in 

 1864. In the year previously, I believe. Prof. Allman dredged 

 the same locality, and communicated to the Royal Society of 

 Edinburgh a paper " On a pre-brachial stage in the develop- 

 ment of Comatula" founded on a single specimen which he took 

 on the occasion. It is a most remarkable circumstance, there- 

 fore, that in the space of about three years the species should 

 have become numerous to the extent alluded to by Major Lang, 

 more than a hundred being taken in one haul of the dredge ! 

 The marine naturalist who year by year finds his favourite speci- 

 mens disappearing on many parts of the coast, will derive 

 some consolation from Major Lang's communication as a set-off to 

 disappointments elsewhere. I notice that Major Lang uses — as I 

 did in 1873 — the nomenclature, Comatula rosacea of Lamarck. 

 Will he forgive me informing him of what I was then ignorant — 

 that Dr. Carpenter, reverting to the previous designation of 

 Freminville, has adopted Antedon rosaceus — and at the same 

 time directing his attention to the two wonderful and exhaustive 

 monographs on the animal in the Philosophical Transactions : — 

 (i) " On the Embryogeny of Aittedon rosaceus," by Sir Wyville 

 Thomson, at page 513, for the year 1865, and (2) " Researches 

 on the Structure, Physiology, and Development of Antedon 

 rosaceus," by Dr. Carpenter, at page 671, for the year 1866? 

 Birmingham, October 20 W. R. Hughes 



Caterpillars 

 If the experiment related below has never been made before, 

 it appears to rae deserving of notice in reference to instinct and 

 evolution. The Luccessful result of the experiment in a single 

 case last year led me to repeat it on a somewhat larger scale 

 this autumn. On September 25 I placed a number of the cater- 

 pillars of Fieris brassicce in boxes, and fed them with cabbage 

 till they began to spin up. As soon as they had attached them- 

 selves by the tail and spun the suspensory girdle, and therefore 

 bejore the exclusion of the chrysalis, I cut the girdle and caused 

 them to hang vertically by the tail in the manner of the Suspensi. 

 More than half of the caterpillars had been ichneumonized, and 

 some accidents to the others finally reduced the number in 

 which the experiment was fairly tried to eight. Of these, three 

 came out successfully, the chrysalids maintaining their hold of the 

 caterpillar-skin until they had succeeded in fastening themselves 

 by their anal hooks to the silk to which the caterpillars were 

 attached The other five, as might have been expected of all, 

 fell to the ground for want of the suspensory girdle. Counting 

 the case last year, here then are no less than four out of nine 

 . caterpillars of the Succincti, when artificially placed in the con- 

 ditions of the Suspensi, adapting themselves to circumstances so 

 greatly changed, and whether by plasticity of instinct or rever- 

 sion to ancestral habit accomplishing a very difficult operation 

 no less successfully. J. A. OsBORNE 



Milford, Letterkenny, October 14 



Electro-Capillary Phenomena 



The electro- capillary machine of Lippmann and his capillary 

 electrometer, besides the capillary electroscope of Werner 

 Siemens and the electro-chemical relay of Wheatstone are all 

 illustrations of a phenomenon resulting from application of an 

 electric current. I am not aware that the converse phenomenon 

 is so generally known, namely, that the motion of the mercury 

 in the [.\xht produces an electric current. If we substitute a gal- 

 vanometer for the battery in a Lippmann capillary machine and 

 move the lever by hand, the galvanometer needle is deflected. 

 Similarly, if in any of the electro-capillary electrometers a gal- 

 vanometer is substituted for the battery and the bubble caused 

 to move by mechanical action, electrical currents are produced 

 which deflect the galvanometer needle. 



The following small instrument may serve to show this action 

 for lecture purposes : — a a is a glass tube of any convenient bore, 

 say 15 to 20 millimetres, by 300 mm. length ; 

 ^ is a cork fitting tightly into the middle of 

 the tube, and perforated in two places 

 where are inserted — at c a tube of | mm. 

 bore, slightly longer than' the cork is thick, 

 and at d z. longer tube, extending half way {f 

 into both compartments. The ends of the 

 tube a a are stopped by the corks e e, 

 through which pass the platinum -wirtsfg. 

 vSufficient mercury to quarter fill each com- 

 partment is introduced into the tube a a, 

 with a small quantity of diluted sulphuric 

 acid. The apparatus being now sealed up, 

 the wires/" and ^ are connected to the ter- 

 minals of a somewhat delicate galvanometer. 



By inverting the tube, as is done with an 

 hour or egg-glass, a current flows through 

 the galvanometer so long as any mercury 

 runs through the tube c (the tube d is an 

 air-tube simply). Reinverting the tube a 

 gives a current in an opposite direction, the 

 platinum wire from that compartment from 

 which the mercury flows always being the 

 zincode of the electrical system. The cur- 

 rent decreases with the mercury in the upper 

 chamber as it falls, being a maximum with 

 greatest head of mercury, and falling to 

 nothing when all the mercury has dropped through. By any 

 arrangement maintaining a constant head of mercury a constart 

 current may be maintained. 



Such an apparatus is especially useful in an electrical labo- 

 ratory where weak currents are required for the adjustment oi 

 delicate galvanometers, or where the heating effect of currents 

 of greater intensity and quantity are required to be avoided. 

 The apparatus can be made in glass and hermetically sealed. A 

 tube like the above placed on a stand which will allow it tc 

 revolve in a vertical plane, and fitted with a commutator, can be 

 made to give a constant current in one direction, and is always 

 ready to hand. 



With a filter funnel the tube of which is drawn out to a fin« 

 point placed above a vessel containing mercury and acidulated 

 water (wires being led from the funnel and lower vessel to tht 

 galvanometer) some interesting results are to be noticed whicl 

 serve to throw considerable light on the action in electro-capil< 

 lary apparatus. It will be found that when the mercury breaks 

 away from the funnel at too great height the mercuria 

 column becomes discontinuous, the circuit is interrupted, and o: 

 course no current passes through the galvanometer ; and whet 

 the funnel is brought so close to the lower vessel as to give onlj 

 a continuous column, the current is on short circuit and the gal 

 vanometer needle undeflected. There is a point, consequently, 

 between these two positions giving a maximum current in th( 

 outer circuit, and this is easily found experimentally. 



P. HlGGS 



THE CAPERCAILZIE IN NORTHUMBERLANL 



A SHORT time back an account appeared in a New 

 castle paper of the occurrence of the C ipercailzi< 

 at Lilburn, in the north of Northumberland. Of course 

 it was also stated that the bird had been shot. Th( 

 account was " descriptive,'' and the writer evidentl} 

 thought he was noting a fact worth telling, for he hac 



