Maucii 1, 1SG5.] 



SCIEN CE-GOSSIP. 



69 



MICEOSCOPY. 



Pollen Grains of Cedae. — I have a small quan- 

 tity of the Pollen of the Cedar of Lebanon {Cedrua 

 Libani), which foi'ms an interesting- ohject for the 

 microscope. I shall be happy to dole out my little 

 stock, as far as it will go, to any who like to send 

 me a stamped envelope. W. H. G., 19, Claremont 

 Square, N. 



Balsam and Chloeopoum. — (In answer to W. G.) 

 — This liquid is very convenient in some cases ; as air- 

 bubbles are much more easily got rid of than when 

 undiluted Canada balsam is used. It also dries 

 readily, as the chloroform evaporates very quickly, 

 for which i-eason it must be preserved in a closely- 

 stoppered bottle. It has been said that this mixture 

 becomes cloudy -with long keeping, but I have not 

 found it so in any cases where I have used it. 

 Should it, however, become so, a little heat will 

 readily dispel the opacity. — Davies on Mounting 

 Microscopic Objects. 



Air-Bladdeks of Tisn. — The following account 

 of a microscoi)ical observation may possibly be new to 

 some of the readers of the Science Gossip. — In pre- 

 pai-ing some fish which had been angled the previous 

 day, the air-bladders being unusually large were pre- 

 served, and as they promised to be of microscopical 

 interest they were submitted to the instrument. In 

 the blood-vessels interlacing them the corpuscles 

 ■were observed to be still in active circulation after 

 a period of some fifteen hours of their being caught 

 — an instance of the extraordinary vitahty of the life 

 principle. Similar observations may facilitate the 

 investigation of this wondrous and novel spectacle to 

 the young microscopist. The fish, I have subsequently 

 understood, were perch, a species unusually tenacious 

 of life, and predatory in their habits. — T. R. 



Ascertaining the Magnifying Power of 

 Glasses. — (In reply to T. 0.)— The apparatus re- 

 quisite consists of a micrometer slide graduated into 

 thousandths of an inch, each tenth division being 

 marked by a longer line ; or two separate slides, one 

 graduated into "thousandths, the other into hun- 

 dredths of an inch; and an ivory scale graduated 

 into inches, tenths, and hundredths. _ The simplest 

 method is that by double-sight, as it is called. The 

 micrometer slide is placed upon the stage, the hues 

 brought into focus, and the image of one of the 

 interspaces, as seen upon the stage with the open 

 eye, not used in looking through the microscope, is 

 measured with compasses. By then dividing the 

 measure of the image of the space by the known 

 measure of the uumagnified space, the quotient is 

 the required magnifying power. Thus, if the space 

 on the micrometer scale is equal to the 1-lOOth of 

 an inch, and the image of the magnified space cor- 

 responds to 5-lOths of an inch, the space is magnified 

 50 times: t^h-y^=50. — Micrograjjhical Dictionary. 



EoRAMiNiFERA. — It is now Well known that 

 from common chalk it is an easy matter to obtain 

 interesting specimens of Foraminifera. Scrape 

 a sm.all quantity of chalk from the mass and shake 

 it in water; leave this a few mmutes, pour the 

 w^ater away and add a fresh quantity, shake 

 up as before, and repeat two or three times. Take 

 a little of the residue, and spread it upon the 

 slide, and when quite dry add a little turpentine. 

 AVhen viewed v»ith a power of _ 250 diameters 

 this will generally show the organisms very well. 



If it is desired to preserve the sHdes, they may be 

 then mounted in Canada balsam. Mr. Guyon ob- 

 serves that the accumulation of the powder, by the 

 action of the rain or exposure to the atmospheric 

 action, at the foot or any i^r ejection of the chalk 

 cliffs, will afford us better specimens than that which 

 is " scraped," as the organisms are less broken ui 

 the former. When the Foraminifera are of a larger 

 size, though transparent enough to be mounted in 

 balsam,' the air must be first expelled from the inte- 

 rior, otherwise the objects will be altogether unsatis- 

 factory. To accomplish this they must be immersed 

 in turpentine and submitted to the action of the air- 

 pump. So diificult is it to get rid of this enemy that 

 it is often necessary to employ three or foui- exhaus- 

 tions, leaving them for some time under each. "When 

 all air has given place to the turpentine, they must 

 be mounted in the ordinary way. — Davies on Micro- 

 scopic Objects. 



On Collecting Objects for tue Microscope. — 

 The following will be found, on an excursion, a useful 

 additiontothe collector's stock of wide-neckedbottles. 

 Take the smallest sized japanned sandwich-box, about 

 four or five inches long, and a quantity of waste 

 paper — old envelopes, and letters torn so that when 

 folded across the pieces whl go easily into the box. 

 On arriving at a likely spot by the side of a pool or 

 ditch, a sample of the produce, whether conferva, 

 bit of rotten stick, or what not, is placed between 

 the folds of one of the bits of waste paper and con- 

 signed to the box, the process being repeated as 

 often as agreeable during the ramble. On returning 

 home, the first thing to be done is to transfer the 

 contents of the papers to glasses or jars of water, 

 leaving them till next morning, when the observer's 

 game will be found in excellent ordei', and ready for 

 the live box or glass slide. The writer has no v.ush 

 to disparage the bottling system ; a well-corked wide- 

 necked bottle is undoubtedly the best thmg, but half- 

 a-dozen such bottles are rather cumbrous, and are 

 soon filled in a productive locality. AVhen this hap- 

 pens, the hunter would be glad to be able to go ou 

 collecting and storing in a space no larger than a 

 pocket-book from twelve to twenty good gatherings. 

 Even the most fragile and delicate microscopic forms 

 may be thus brought home uninjured— T-o/i-o.r, Vorti 

 cel'la. Rotifers, Entomostraca, and, in fact, all the 

 various classes of organisms sought for by those 

 who practise this branch of fishery. Tliose who 

 desire to command a more extensive range than is 

 afforded by the invaluable hook-ended walking-stick 

 are generally told to provide themselves with a cheap 

 fishing-rod. A much better thing is the handle of 

 an angler's landing-net. These instruments may be 

 had at the fishing-tackle shops, vvith two or three 

 lengths sliding one within the other Hke the draws 

 of a telescope, and from their construction, the 

 lengths cannot separate when dragging to land a 

 heavy mass of weeds, as the joints of a fishing-rod 

 are apt to diO.— Robert C. Douglas. 



British Salmon. — Dr. A. Gilnther is engaged in 

 a revision of the British Salmonidfe, and, from the 

 materials already at his command, is enabled to aflirm 

 that we have at least four non-migratory species 

 which have not hitherto been recognized— one found 

 in the mountain loclis of AVales, one in Ireland, one 

 in tlie lakes of the Orkneys, and one in the Frith 

 of Forth. 



