244 



NATURE 



{Jan. 25, 1872 



variations in the intensity of these solar currents may be followed 

 by a disturbance in the terrestrial magnetism at any time, yet 

 such disturbance should be at a maximum at the equinoxes {as is 

 the case by Secchi's law), because then the sun is most favour- 

 ably situated for causing such effects. 



In this hypothesis the source of the earth's permanent mag- 

 netism is not included, but simply the cause of the close con- 

 nection between solar eruption and the disturbance of the terres- 

 trial magnetic elements. F. A. Fleming 



Mechanism of Flexion and Extension in Birds' 

 Wings 



UiNTjER the above heading in your issue of January 18, 1S72, 

 Dr. Elliot Coues deccribes the peculiar movements m.ade by the 

 bones of the wing of the bird in flexion and extension. It may 

 interest some of your readers to know that those movements were 

 minutely described and elaborately illustrated in a paper by Dr. 

 J. Bell Pettigrew, communicated to the Linnean Society in June 

 1867, and published in vol. xxvi. of the Transactions of that 

 bo'-'y. MiLLEN COUGHTREY 



Edinburgh University, Jan. 22 



Elisee Reclus 



A MEMORIAL addressed to the "Commission des graces," 

 sitting at Versailles, and most influentially signed by many of the 

 leading scientific men in London, was presented at Versailles on 

 the 3rd inst. 



It is an appeal for commutation of sentence of deportation 

 passed on Elisee Reclus, the well known French geographer, 

 author of " La Terre," an admirable popular work on physical 

 geography (now being introduced as an English work* by 

 iMessrs. Ctapman and Hall), and various other books. 



A paragraph having appeared in several of the daily papers 

 announcing that M. Reclus's sentence had been already commuted 

 to simple banishment, I regret to state that he is siill a prisoner 

 at Versailles, although it is hoped the appeals made in his favour 

 may produce the desired result. 



The petition to the CoramisL-ion in favour of Elisee Reclus 

 was signed by the president of the Geological Society (Mr. 

 Prestwich), Sir Charles Lyell, Bart., Mr. G. Poulett Scropie, 

 Profs. Owen, Ramsay, Williamson, Duncan, Atkinson, Morris, 

 Rupert Jone=, Tennant, Messrs. Evans, Forties, Gwyn Jeffreys, 

 Drs. Carpenter, Richardson, and many others. 



A stcoi d petition signed by Sir Henry Rawlinson, Sir John 

 Lubbock, Bart., Mr. Darwin, and other men of eminence, was 

 addressed to M. Thiers in favour of Elisee Reclus. 



Surely the time for an amnesty has arrived. 



British Museum, January 23 H. Woodward 



NOTES ON MICROSCOPY 



MOUNTING IN Glycerine.— It is often found de- 

 sirable to mount very thin objects in glycerine, 

 for which no special cell is requisite, and in which 

 the thickness of a cell would be a disadvantage. To 

 accomplish this was often a work of difficulty, since the 

 presence of the smallest amount of glycerine outside the 

 thin glass cover prevented the adhesion of the luting by 

 means of which the cover was to be secured to the slide. 

 Since the introduction of gum dammar dissolved in 

 benzole to the attention of microscopists, this disadvant- 

 age has almost wholly vanished. It is now comparatively 

 easy to mount such objects in the following manner. A 

 small drop of glycerine, just enough for the purpose, is 

 let fall in the centre of an ordinary cleaned slide, the ob- 

 ject is then placed in the glycerine, having been pre- 

 viously soaked in benzole if any difficulty was likely to 

 be experienced on account of contained air ; a cover (say 

 three quarters square) of thin glass is placed over the 

 object and pressed down, taking care that the object re- 

 mains in the centre ; a wire clip then applied holds the 

 cover in its place. If too much glycerine has been used, 

 blotting-paper or a camel-hair pencil will remove all that 

 issues beyond the edge of the cover. If too little, the 



* Sections I. and 11. of this work are "already published; Section-, III. 

 and IV. are now in the press. . _ 



addition of more at one edge will supply the deficiency, 

 and the superfluous remainder may be wiped away. Thus 

 secured by the clip the edges of the cover may be painted 

 round with gum dammar in benzole, and when dry and 

 firm (in a day or two) the clip may be removed, and the 

 surface of the slide carefully washed to remove any trace 

 of glycerine. The clip may be replaced, and a second 

 thin coating of dammar laid over the first, or old gold 

 size may be used instead. When this is dry "papering" 

 the slide in the usual way helps to provide against acci- 

 dent. The advantages derived from the use of this 

 method are chiefly the facility with which the cover is 

 attached, notwithstanding the presence of a trace of gly- 

 cerine on the slide and cover, which it is not easy to 

 avoid ; and, so far as the experience of two years can 

 vouch, freedom from leakage afterwards, especially when 

 covered with paper. This plan succeeds best with objects 

 as thin as the minute spores of fungi, delicate hairs, &c,, 

 and a one-eighth objective may be employed in their 

 examination. 



The Asci in Peziza. — Having left a specimen of 

 Pi-::ha hnniosa for a long time in water until it became 

 c[uite soft and pul]5y, I was curious to examine it in such 

 condition, and found that the hymenium presented a 

 singular appearance. All the paraphyses had become 

 dissolved into a granular mass, retaining still some of their 

 original colour. Amongst these the asci were free, and there 

 were some free sporidia. I n their normal condition the asci 

 are cylindrical, and the sporidia are arranged in a single 

 series, but in the present case the asci had become 

 perfectly spherical, from the absence of all lateral pres- 

 sure, and the sporidia were clustered in the centre. The 

 line of the external surface of the asci was very distinct 

 amongst the orange-tinted granular mass, and the eight 

 sporidia could be counted within. There could be no 

 doubt of the presence of an investing membrane, but of 

 a much more elastic nature than has been supposed. 

 This fact seems to suggest the probability that more or 

 less lateral compression in the hymenium may influence 

 the character of the asci, and that cylindrical, or clavate 

 and elliptical asci, indicate more or less of lateral pressure 

 during development. 



S.'^CRED Thread.— The sacred thread, or at least one 

 kind of thread held sacred to religious purposes by the 

 Brahmins in India, is derived from the stem of a species 

 of \vater lily — some say the Nelunibium spcciosiim, others 

 Nymp/ura ediilis. At any rate under the microscope it 

 exhibits a mass of spirals, unwinding in ribbons of four 

 or five threads laterally united. There is no trace of cells 

 mixed up with it, and the spiral threads are as clean as 

 if they had been removed with special care for micro- 

 scopical purposes. 



Hop Mould. — A new mould has made its appearance 

 during the past autumn on the spent hops so common 

 about Burton-on-Trent. It formed large dense patches of 

 a bright salmon colour, sometimes several inches in 

 length and breadth, upon the sombre hops, and could not 

 have escaped notice had it appeared in previous years. 

 The structure of this mould seems to be closely allied to 

 that of Oi Uuiii, whilst in many respects it reminds one of 

 Spoycndoiicina casci. The creeping mycelium gives rise 

 to branched threads, which become divided into strings 

 of oval conidia or spores. The mould refuses to develop 

 itself artificially, so that the mode in which the beaded 

 spores were produced was not absolutely determined. 

 Directly the threads come in contact with fluid of any 

 kind they are resolved into a mass of oval cells or 

 spores. Specimens of this mould have been published and 

 distributed in Cooke's " Fifth Century of British Fungi " 

 under the name of Oidium aiiraniiuin, a rather unfortu- 

 nate specific name, since another member of the same 

 genus which appeared nearly simultaneously on the Con- 

 tinent has been called Oidium aurantiacum. 



M. C. C. 



