FEiiBnARY, 1902.] 



KNOWLEDGE 



45 



just faintly acid to the taste. To obtain perfect casts the 

 process must ba carried out very slowly, adding drop by 

 dro]> to th." watch glass containing the specimen. When 

 decalcification is comi)lete, the resulting cast should be 

 carefully removed with a pi])ette, and deposited in a spot 

 of gum on a slip. They will not stand transference with 

 a brush without damage. . 



KoTE. — For particiihtrn regardbty the Distribution of 

 Material, gee below. 





Conducted by M. I.Crp§s. 



Pond Ccu.i.K I'lNi .Mumu uv ^t<l^■Tll. — Mr. C. F. Rousselet 

 hii.s arranged to i)roviiie for each month a list of the material 

 that should be looked for and likely to be found at that period 

 of the year : — 



PoNi")-i.ii T. Coi.i.EcTiNu IN Fkhriauv. — In the early part ot 

 the year when the weather is still cold and ponds are covered 

 with ice, some Infusoria may be found in abundance, particularly 

 the various species of Vorticella — CurcAesium poliji.inuiii, 

 Zoothamnium (irbuscnla, Kpislylis ttaricaiis -attached to sub- 

 merged rootlets. 



Rotifera to be looked for in lakes and ponds, particularly 

 duck ponds. — Aiiunien aiulcata, Anuraea cochlearis, Ai'jildnclina 

 primlnntii and /irii/litirelli, Xntkolca scappa, Poli/arthni ji/ati/p- 

 terii, l\iii-liliiiiit (lericxa, Synchneta tremuhi. The water plants 

 having mostly died down, the following fixed forms are found 

 attached on Anacharis or on submerged rootlets of plants, or of 

 trees growing near the edge of ponds and lakes : — Meliccrla 

 liiif/fng, Liiiiiiia^ centlophiflli, Slej)li(iii'irei-iiii ciehhnriiii, Flosen- 

 lariii r.trniila and others, Uecistes criiHldUinna and others. 



Two-Si'K,Ki> Fine Ad.hstmknt.s. — At first sight a proposition 

 that a microscope should be provided with the equivalent of 

 two fine adjustments, by means of which both an extremely 

 slow and a rather more rapid movement might be imparted, in 

 addition to a well-fitted coarse adjustment, would seem to be 

 scarcely worthy of discussion. Consideration leads one to 

 believe that it might occasionally be convenient, but actual 

 working with the fitting itself puts the whole question beyond 

 speculation. 



Any mechanical contrivance which enables those who have to 

 work rapidly to attain their results with increased facility is 

 worthy of commendation, and its virtues should be made known. 



An interesting ])aper by Mr. Ashe, with illustrations of tbe 

 methods of application o£ two-speed fine adjustments. a])pe,ars 

 in the .I'lunuil nf tlie Qiipl.rll Mirmxrupirid Cluh for November. 

 Reichert, of Vienna, Bad already anticipated the idea by in- 

 corporating a similar arrangement in his large model microscope, 

 but Mr. Ashe has rendered piacticjl the fitting of the device to 

 direct-acting screw fine adjustments of the Continental type, 

 and. in conjunction with Messrs. R and J. Beck, has neatly 

 contrived a manner of ap)dying it to such instruments as have a 

 fine .adjustment, worked by a lever in the liml). 



It consists of two concentric milled heads, working respectively 

 coarse and fine screws, the former being controlled by the up])er 

 milled head, ami at its point making contact with the lever. 

 This operates through the lower milled head, which works on 

 the fine thread, so that without real thought the fingers can 

 move from one milled head to the other as a quick or slow 

 motion may be required. 



As a two-speed adjustment can be fitted to different classes of 

 microscopes subsetjuent to manufacture, it is likely that many 

 workers may feel disposed to have it experimentally added to 

 their instruments. 



I\(KK.\siN(; Effect with the Anm: Ii.ldminator.— The 

 Abbe Illuminator has for some time been regarded as such an 



inferior condenser for all who aspire to accurate work, that little 

 devices which might render it more efficient have been often 

 overlooked. When the enormous number of them that are iu 

 use in all parts of the world is taken into consideration, every 

 hint regarding them is of importance. 



When the edge of the flame is foc;ussed with an .\.bbe Illu- 

 minator and the back lens of the objective e.xamined through 

 the tube of the microscope, the black spots, which indicate the 

 limit of aplanatism, ap|)ear when the iris is hut slightly opened. 

 If, however, the flat of the flame be used and carefully focussed, 

 a much larger iris opening can be emploj'ed before the black 

 spots appear ; in other words, the efficiency of the condenser 

 can be very materially increased for critical illumination and a 

 larger solid cone obtained by using the flat of the flame as the 

 source of illumination instead of the edge. 



FoR.vMiNUFRA.— As notified in the January number, material 

 is now at the disposal of readers of Knowi.euce who may wish 

 to practise for themselves the directions given by Mr. Earland 

 in his article on " Foraminifera.'' There are two kinds— (1) 

 cleaned shore sand from Bognor, Sussex— " washings " or 

 " floatings "' — and ('2) uucleaned dredged sand from shallow 

 water, Barbados, West Indies. It is requested that applicants 

 for this will enclose a stamped tie-on label addressed to them- 

 selves, and state which kind of material they wish for. 

 NOTES AND QUERIES, 

 ir. .1. F. — I have made inquiry with regard to the American 

 Styrax Gum Liquidambar Styraciflua, and find that the liquid- 

 ambar, which is the medium in which diatoms should be 

 mounted, is almost unprocurable just now, and am told that one 

 well-known diatom-mounter paid 50 francs for a few grammes 

 of this medium. Grubler in his catalogue of re-agents, etc., 

 includes Styrax solution in 10-gramme or lOO-gramme tubes at 

 a nominal price. 



G. J. Maurice. — The subject of the causation of colorisation 

 of hair is undoubtedly an interesting one, but I am not 

 acquainted with any work which deals with the subject scientifi- 

 cally. You would probably find an opportunity for useful work 

 if you de.alt with this subject yourself. 



/. /•'. Jleiritt. — I have submitted the specimens and your 

 notes to an expert on these matters, and his reply is as follows ; — 

 "My conclusion is that they are Chlnraster ielrarhynehus, hat 

 they alter very much in form during their circle of life. The 

 reproduction is by longitudinal fission, and at this time they 

 develop the eight setase appendages preparatory to fission. I 

 saw the creature on its side, and on the anterior end with the 

 flagella equally separated and seeming to curve upwards. 

 When on its side I saw at the anterior extremity two half-round 

 projections ; these were (I think preparatory to fission) the 

 rhynchi or beaks from whence issue the flagella.'' 



Reader 'if '^ Kiinirhdiie." — In the January number a brief 

 reply was inserted to this correspondent. He has since sent a 

 fair quantity of material found growing in a water supply pipe. 

 This has been examined by correspondents, who have identified 

 it as belonging to the Polyzoa and to be I'aliiiVreUa Ehi-eiiherriii. 

 There are no polypidea, they have all died and disappeared, but 

 there are winter buds. 



Three other correspondents have sent letters with regard to 

 Paludicella. 



One mentions that Prof. Allman's fine Monograi)h of the 

 British Fresh- water Polyzoa (Ray Society's Publication, 18.56- 

 1857) is the work to be consulted. Prof. E. Ray Lankester, 

 in the '.Hh edition of the " Encyclopaedia Britannica," examines 

 in some detail /'aluilirella Elnenbei-f/ii, which he takes as a type 

 for comi)arison with the other groups of the Polyzoan class. 

 The fresh-water groups of the class are also the subject of a 

 Monograph by M. J. Jullien in the Hull. Sue. Zonl. de France, 

 Xlli. Further, he points out that " the growths and organisms 

 which establish themselves in the numerous systems of conduits, 

 mains, and other closed channels existing in the kingdom, and 

 used to convey w.iters of very great variety analytically, derived 

 from sources difl'ering from the superficial to the deeply 

 subterranean, and delivered under a hundred or two of conditions 

 which tend to foster vegetative or animal life, or both, would 

 form a subject for a very extensive Monograph of their own." 



The other correspondent gives the following information : — 

 " Paludicella is a fresh-water genus of the class ' Bryozoi ' 

 (Polyzoa), sub-class Ectoprocta, order Gymnolaema, sub-order 



