70 



KNOWLEDGE 



[March 1, 1901. 



respect. It must be remembered that the horseshoe foot is 

 more easily gripped and held tirmly in its case than the tripod, 

 l)ut ;i strong and neat fitting for tlie latter ought not to be 

 beyond the powers of the ingenious to contrive. 



It may be fearlessly stated that a good day is coming yet for 

 British microscopes if the makers do but set their house in order, 

 and in addition to providing the most sound and accurate instru- 

 ment that can be, they give due consideration to every detail 

 which will make them acceptable to those who are influenced by 

 appearance. There is no disgrace in making a microscope and 

 its case ornamental as well as useful. 



St.vininii Living BAfii.i.i. — We have had placed in our 

 hands an interesting paper by Mons. A. Certes dealing with the 

 selective colouring power of the spore-bearing filaments of the 

 liriiui Sjiiritlxirillas giga^ with methylene blue, and the following 

 is a brief ?vs!/«/c' of it. 



He remarks that the experiments of Brandt, Henneguy and 

 himself, dating from 1881, jirove that living protoplasm can 

 absorb certain aniline colours, but little has been done by 

 biologists in the study of the action of colouring substances on 

 living microbes. It has been found that certain microbes cease 

 to live on being stained, others absorb the stain and still remain 

 alive, while others do not absorb the stain either alive or dead. 



The difficulty of making observations on selective coloration 

 is obvious on such delicate subjects as bacteria, but M. Certes 

 was fortunate in discovering the SpirnlKirilhii' g/i/as in the 

 reservoirs at Aden ; the length of these is usually 150 — 160 

 mikrons, but they are occasionally found 400 mikrons long. 



These organisms placed in a weak solution of methylene blue 

 continue to move about with the same activity as before, and 

 the stained specimens can be preserved alive until the following 

 day if care be taken not to exclude oxygen. 



The effect of the stain varies according to the stage of 

 development of the bacilli. During the first two or three days 

 the living specimens are entirely and uniformly stained in blue 

 exactly like dead specimens. 



When the period of sporulation commences, alongside of the 

 totally stained bacilli, the presence of bacilli of different shapes 

 is observed, partially stained and much more clearly. In the 

 same specimens are coloured rings in juxtaposition to uncoloured 

 rings, grouped in the most varied manner and without any 

 apparent fixed rule. 



The spore-bearing individuals which appear a little after, give 

 the clue to these selective coloration phenomena, which acquire 

 a still greater clearness when the specimens are larger — as the 

 turns of the spiral are less serrated, and the spore-bearing 

 bacilli move more slowly in zig-zig fashion. One sees, therefore, 

 that the spores, while refractive, have, except in rare cases, 

 absorbed the colouring matter, and that the filaments which 

 carry them are, in general, more feebly coloured, sometimes even 

 uncoloured, and that in those specimens whose spores are 

 localised at one extremity on a fixed point on the filament, the 

 rings which carry the spores are almost always uncoloured. 



Success largely depends on the colouring re-agents that are 

 used. The finest quality of Ehrlich's blue and the chemically 

 pure methylene blue of Gri'ibler and IMchst in very weak solu- 

 tion are recommended, and they should be used at the precise 

 moment when the first sporule-bearing individuals appear. 



These phenomena are only visible in the living state ; dead 

 specimens stain so rapidly and uniformly that it is extremely 

 difficult to obtain preparations in which the differentiated 

 coloration is distinctly visible. 



Xf.W ArP.\R.\TUS DKSCRiliEIl i!Y Manuf.\ctureks. — We 

 have received from Messrs. A. E. Staley & Co., of 35, Alderman- 

 bury, London, some very interesting notes regarding the 

 microscopes and accessories manufactured by Tlic Jlau^th if- 

 Lnwh (Ijilicii! r-.,, ItiH'hester, Ncn- Yuri:, U.S.A. 



It is, unfortunately, impossible to reproduce the details in 

 their entiret3', but we have much pleasure in calling attention 

 to the fact that Messrs. Staley have been appointed agents for 

 Great Britain for these famous instruments. 



A perusal of the English edition of ^lessrs. Bauscb & Lomb's 

 catalogue discloses the fact that prices have been considerably 

 modified for the English market. 



Those who have a preference for the Continental type of 

 stand will find an assortment of these of varying sizes, while 

 microscopists who are interested in objectives and apparatus 

 will find it well worth their while to peruse the handsome 

 catalogue. 



The Bausch and Lomb microscopes have a great reputation 

 in the United States, and are, undoubtedly, soundly constructed, 

 well finished, and in the English catalogue moderately priced. 



ir. Watson i(- Sniix, 313, High IluJhoni. H'.^'. — A new form 

 of sterilizable needle for blood examination, designed by Drs. 

 Slater and Spitta. It is of metal throughout, can be sterilized, 

 and remains so when carried in the pocket. It is .self-contained, 

 and carries a reserve of lancet-pointed needles in its recessed end 



Notes and Queries. — Commuu/cations and enqxiiries cm 

 J[/cro.scopical inatter.t are cordially invited, and shoidd he 

 addressed to M. I. CROSS, Knowi-EDcf, Office, ,^2(i, Hicih 

 Ilolhorn, W.C. 



NOTES ON COMETS AND METEORS. 



By W. F. Denning, f.r.a.s. 



OiACOBlNl's Comet. — The small comet discovered at Nice, on 

 December 20th, was very faint, and it had already passed its peri- 

 helion. Becoming faint«r with increased distance from the earth it 

 w.TS only observed in large telescopes, and has now practically passed 

 beyond the range of risibility. From observations between December 

 2-tth, 1900, and January 14tli, IHOl, Prof. Krentz, of Kiel, finds that 

 the comet revolves in an elliptic orbit, with a period of about 6'88 

 years, so that it belongs to the Jovian t^amily. It passed through 

 perihelion on November 28th, 1900, and the elements of its orbit bear 

 a resemblance to those of Wolf's comet of 188i. and Barnard's comet 

 of 1892. The comet being a periodic one of interesting character, it 

 is to be hoped that position-observations will be secured over a 

 sufficiently long interval to enable a good definitive orbit to be derived 

 from them. On JIarch 6th the place of tlie comet will be R.A. 

 4h. 7m. .53s., Deo. 10° 1' ,8., so that it will be near :Mii-,i Ceti. 



Bboesen's Comet. — Tliis object ought to be fairly well visible in 

 March, but in view of the fact that its continued existence is some- 

 what questionable, we cannot look forward with confidence to tlie 

 re-appearance and discovery of the comet. First seen by Brorsen at 

 Kiel on February 26th, 18-tS, it was found to be revolving in an 

 elliptical orbit with a jieriod of about 5i years, and it was satis- 

 factorily re. observed in 1857, 18G8, 1873, and 1879, but escaped notice 

 at the last three returns in 1885, 1890, and 1896. Slioiild the comet 

 elude detection during the present spring there will be no alternative 

 but to conclude that, like the double comet of Biela, it must be num- 

 bered with the lost comets. Hind pointed out in Ast. Nach., 3271, 

 that the orbit of Brorsen's comet and of Denning's comet (T. 1891) 

 intersect in long. 285, and that in April, 1881, the two objects must 

 have been dose to one another near the point of intersection. He 

 was led to the conjecture that Brorsen's comet, on its recession from 

 perihelion after it was last observed in 1879. may have met with a 

 catastrophe, bringing about its dieintegi'ation and causing one portion 

 of it to return in tlie aspect and orbit of Denning's comet of 1891. 

 Dr. Scliulhuf supported these conclusions, and pointed out {Ast. Nach,, 

 3276) that the point of intersection of the two orbits coincides with 

 the place of i heir nearest approach to the planet Jupiter, Dr. Lamp 

 has also examined this interesting question, and found that the two 

 comets passed through the corresponding points of their orbits on 

 January 17th and January 23rd, 1881, respectively. The least dis- 

 tance between the two orbits was 199 radii of the earth, I'here is 

 very little doubt therefore that a close conjunction of the two comets 

 occurred early in 1881, but whether or not this indicates the actual 

 disintegration of Brorsen's comet on that occasion is open to question. 

 The approach of the two bodies may have been quite accidental. In 

 any case, the re-dctection either of Brorsen's comet of 1846 or of 

 Denning's comet of 1894 will be important, as affording materials for 

 the further investigation of the idea of their conned ion. 



Datlight Fireball of Janitabt 6tii. — This object, which 

 ajipcared in bright sunshine, 52 minutes after noon, was quite of an 

 exceptional character. It was observed by several persons in Glasgow. 

 " T. 11." says he was walking along Great Westei'n Road a few 

 minutes before 1 p.m. when the meteor tlashed across the north- 

 western sky. " L. D " describes the object as bursting like a ball of 

 fire among the hedges near the Catholic cemetery as observed from 

 Lambhill Road. Another writer noticed it from AVhiteinch Park, 

 and states that its flight was in the direction from X.E. to W, It 

 was not like an ordinary falling star, but resemliled a rocket with a 

 long streaming tail. It apparently exploded on Scotstownliill. As 

 seen from Rosneath the meteor appeared as a ball of fire with a tail. 

 It darted between the trees in a westerly direction about 20 feet off 

 the ground. At Crossmylcof it looked like a roi'kct flying in a north- 

 westerly direction. It was of considerable size, the glowing mass 

 forming the head being as large as a bowling ball with a fiery tail 

 attached. .At Durisdeer, Dumfries, '' J, W. W." refers to the meteor 

 as a large silver ball, with a long tail, appearing in a north-westerly 

 direction. \i Craighat, Killearn, X.B., the object vanished 12" above 



