May, 1906.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



441 



tension, became increased, these bodies might assume 

 the forms of minute spherical drops, like those found 

 in ordinary fluids. More recently, on microscopically 

 examining- certain of these drops, it was found that 

 they behaved like living infusoria, and were in such 

 active motion that the eye could scarcely follow them. 

 The drops, which had somewhat the consistence of 

 olive oil, were not absolutely spherical, but they fre- 

 quently have a funicular depression from the middle of 

 which a ray is directed to the centre of the drop. The 

 drops change very suddenly in form, and assume a 

 serpentine shape. In other cases they appear to bud 

 out or become divided, and give rise to several new 

 particles by a species of spontaneous self-division. The 

 changes which take place are similar to those observed 

 in the case of micro-organisms, but in this instance they 

 are no doubt caused bv vorv slight variations of tem- 

 perature. 



Messrs. Flatters and Garnett's Catalogue. 



Messrs. Flatters and Garnett, of Manchester, have 

 sent me a new catalogue which they have just issued. 

 The first part contains a classified list of slides of their 

 own mounting, the majority of which are sold at the 

 very modest price of 6d. each. Amongst these I may 

 mention their excellent Student's Series of Botanical 

 Slides, 48 in all, sold at 21s. the set, or with an explana- 

 tory book of diagrams is. extra. The second part of 

 the catalogue contains a list of microscopes and 

 accessories by the leading English and Continental 

 makers, and particulars of various mounting and other 

 microscopical requisite.s. Apparatus for the study of 

 pond-life is particularly well represented, and amongst 

 this are various sizes of rectangular glass tanks, made 

 in one piece, for use with hand lenses, and two neat 

 japanned collecting cases containing corked tubes, so 

 arranged that the tubes cannot be upset when the case 

 is placed open upon the ground. 



Microscopical Material. 



By the kindness of Mr. J. Strachan, of Ballyclare, 

 Co. .'Vntrim, I am able to offer to such of my readers as 

 care to apply for it some diatomaceous earth from the 

 deposit at Toome, on the river Bann, Co. Antrim. Ap- 

 plications must be accompanied bv the coupon to be 

 found in the advertisement pages of this issue, together 

 with a stamped and addressed envelope, and, preferably, 

 by a very small box. It is, perhaps, advisable to men- 

 tion that ! not infrequentlv receive applications for 

 similar material, which, in spite of clear instructions, 

 are accompanied neither by envelope nor stamp, and 

 to these I feel mvself justified in paving no attention. 



Notes and Queries. 



C. T. D., Hayward's Heath. — .\ oiio-'.ixtli inch olijerlivc 

 will probably show you most of what you w ant to sec willi 

 regard to animal hairs, and for this power a condenser is 

 necessary if you wish iho objective lo perform at ils best. 

 The pigment gr.-uuilcs r.in generally be seen if the hair is 

 a transparent one, but if not you will need lo cut loniritu- 

 din.'il seclions by nieans of some embedding process. I do 

 not Unow of any work that has been done on the pigment 

 granules themselves, but a book like Schiifer's " Essenlials 

 of Hislology," describes human hairs and their follicles with 

 some detail. 



T. I\ 7"., Aden. — To distinguish diatoms from Kadiolaria, it 

 would be neces.sary to see them in the living state, or to be 

 sufficiently familiar with the frnstnlc or silicions skeleton of 

 the particular species. The Kadiolaria have, for the most 

 prut, skeletons quite unlike the I'rnstnles of the diatoms, whilst 

 tlu! presence of pseudopodia in a living specimen would at once 

 place it amongst the Rhizopoda. Maeckel's epoch-making 



work on the Radiolaria is, of course, authoritative, but the 

 best work of reference is the great monograph in the ■' Chal- 

 lenger " Reports, which contains i.Soo pages and 140 plates, 

 and describes nearly 4,500 species. 



5. C. .M.. Bombay. — A one inch or two-thirds of an inch and 

 a one-sixth of an inch objectives are quite sufficient to examine 

 textile fibres either with or without reagents. An oil-immersion 

 objective would not be suitable for examining micro-chemical 

 reactions, but a one-eighth inch dry lens can be used for certain 

 classes of work. I do not know of any " acid-proof " objec- 

 tives for such work. Personally I keep three special and inex- 

 pensive objectives for this purpose, and when necessary affix a 

 small piece of broken cover-glass with glycerine to the front 

 lens, whilst the microscope has a special glass stage. I know 

 of no differential stains for identifying fibres other than those 

 mentioned in my article on the subject — fuchsine would 

 merely stain the fibres and so help to bring out their structure. 

 It is not necessary to fix the fibres to the slip before staining ; 

 they can be taken up on the point of a needle and transferred 

 from stain to other reagents as desired and only teased out on 

 the slip prior to mounting. I do not think it would be any 

 use trying to cut sections of fibres unless you have any special 

 reason for doing so, in which case a few fibres could be tied 

 together longitudinally and supported in carrot, pith, or 

 paraffin for transverse sectioning. Xor do I think it would be 

 of service to try to cut sections of paper pulp — it would be a 

 most unsatisfactory job at best, but of course if you wished to 

 do so you could dehydrate in alcohol, clear in xylol and 

 embed in paraffin, or you could embed in celloidin, or even 

 freeze direct with ether. 



C. /., Birmini^luan. — For the use of a polarizer and analyser 

 in ordinary work not connected with the special study of 

 crystallographic systems it is only necessary to have some 

 means of knowing when the Nicol prisms are parallel or 

 crossed, and for this purpose four marks or stops go^ apart are 

 sufficient. It is certainly not necessary to get a polarizing 

 prism large enough to cover the back lens of your condenser. 

 Iceland spar is not only expensive, but the expense increases 

 out of all proportion in the larger prisms. Such a prism would 

 moreover necessarily have a most inconvenient length. I 

 should recommend an ordinary polarizer costing about 20s. or 

 30s. (with removable selenite), and with a thread in the mount 

 into which you can screw the optical part of your condenser 

 so as to get more light if necessary. The analyser can be 

 mounted either over the objective or over the eyepiece: the 

 former is the cheaper but causes rather more loss of light ; the 

 latter is more eflective and gives a larger field if of sufficient 

 size. The prism should be removable from the eyepiece. I 

 think you would find Watson's " Universal" Condenser more 

 generally useful than their " Parachromatic," unless you work 

 almost entirely with high powers. 



/. B.. Kclvinsidc. — I do not know of any advanced book which 

 deals with pond and aquarium life and which would enable 

 you to name objects. Such books are written for amateurs 

 and are nectssarily somewhat chatty and discursive. Taking 

 Furneanx's book as a good example of such books, I should 

 say that i' you want more detail you nuist be prepared to 

 study cue or more special branches for yourself with the help 

 of special works dealing with such branches ; for example, one 

 or more volumes of the Cambridge Natural History or of Prof. 

 l\ay Lankester's even more advanced " 1 reatise on Zoology." 

 Veil will find the second volume of Carpenter's "The Micro- 

 scope and its Revelatioi s"ofno littleservice to you in studying 

 microscopic natural history, but I cannot say that it will help 

 you to name many speiimens. That, except for the commonest 

 species, is work for specialists. 



IF. //. B.. Leicester. — I am sorry that I cannot give you any 

 information as to the mounting of diatoms in realgar. I have 

 some specimens of .{mphit'leura pelliicidd mounted in this 

 medium, but I believe they were done by one man, who is a 

 professional mounter. Nor do I know of any solvent for real- 

 gar which does not decompose it, but it is supposed to fuse 

 easily, and as diatoms will stand a good heat I should look upon 

 this method as offering most probabilities of success. I should 

 be grateful if any of my readers could give any information on 

 the matter, as I have been asked this question before. 



[Commiinieations and Enquiries' nn Microicopieal mutters should he 

 adilressed to F. Sliillington Scijies, "Jersey," St. Barnakis RojJ , 

 Cambridge.] 



