April 1, 1S67.] 



HARDWICKE'S SCIENCE-GOSSIP. 



91 



MICROSCOPY. 



Hints to Object Mounters.— The following 

 few bints on mounting objects for tbe microscope 

 may possibly be of service to tbe large number of 

 amateurs who are engaged in tbe study of tbat 

 instrument. Tbese remarks refer to Canada balsam, 

 the medium used for all, excepting certain classes of 

 objects which require to be mounted dry or in some 

 fluid. Eirst, with reference to bottles used to con- 

 tain the balsam and turpentine, I should recommend 

 the wide-mouthed bottles with covers which fit out- 

 side the neck ; this effectually prevents the recur- 

 rence of a constant source of annoyance to those 

 who close their bottles with corks in the ordinary 

 way, for in withdrawing a drop of balsam with the 

 glass rod or wire while mounting an object, it fre- 

 quently happens that the inside of the neck is 

 smeared with it, the cork is presently inserted and 

 when next it is used is stuck fast, and in removing 

 it some small fragments are torn off and probably 

 fall into the balsam, and perhaps sometime or other 

 get into a good mounting and materially injure it ; 

 by adopting the above method this accident will be 

 impossible. It will also be advisable to use the 

 same sort of bottle for tbe turpentine, as it prevents 

 dust and dirt accumulating round the neck, and 

 getting into the preparations. These bottles may 

 be obtained at any glass bottle warehouse; they 

 are manufactured by the York Bottle Company, 

 either with screw covers (which are preferable), or 

 merely tightly fitting covers lined with cork, which 

 answer the purpose perfectly. Turpentine is a 

 most important article in mounting in balsam, and 

 too much care cannot be used in obtaining it pure ; 

 the compound sold in the oilshops is generally a 

 vile mixture, containing but a very small portion of 

 pure turpentine, and quite unfitted for use in mount- 

 ing ; it may, however, be procured of good quality 

 of any respectable chemist, at a cheap rate, and is 

 known as " spirits of turpentine." The following 

 is a method of proceeding which I adopt in mount- 

 ing in Canada balsam objects of great delicacy, 

 which will not bear drying on slides without great 

 risk of damage in removing. The object, on being 

 taken out of the potash or other solution, is 

 thoroughly washed in clean, warm water, and when 

 perfectly clean, immersed in spirits of wine (the 

 ordinary methylated spirit answers perfectly). It 

 should remain for some little time, say half an hour 

 or so, and may then be removed, slightly dried on 

 blotting paper, transferred to the turpentine, re- 

 maining there as long as necessary, and then 

 mounted in balsam in the usual way. In this plan 

 of proceeding it will be seen that the object is 

 never once dried, and is therefore not so liable to 

 get damaged as in the ordinary way of drying on 

 a slide and then removing. I might here mention 



that I do not think the plan of drying on slides 

 and then immersing the whole in turpentine is al- 

 together satisfactory; for however well an object 

 may be washed, it always leaves a trace of im- 

 purity on the slide on which it is dried, and with- 

 out removing it of course this cannot be got rid of. 

 The balsam I prefer is that usually sold at the 

 shops, thinned when necessary with pure spirit of 

 turpentine ; the chloroform and balsam I have no 

 liking for, and must say I have not found it as 

 satisfactory as the unsophisticated article.— G. E. 

 Cox, F.EJI.S., 9, Mincing Lane. 



Whelk Eggs. —Are the readers of Science- 

 Gossip generally aware of the extreme beauty of 

 the membrane enclosing the eggs of the common 

 Whelk {Buccinum tuidatum), when placed under the 

 polarizing apparatus ? The softness of the colouring 

 and the delicate blending of the tints are equalled 

 by few, and surpassed by none, of the polarizing 

 objects with which I am acquainted.. The bunches 

 of whelk's eggs are (as every seaside visitor knows) 

 a " common object of the seashore." I have a few 

 by me, and shall be happy to supply them, as far as 

 they will go, to any one sending a stamped envelope 

 to Rev. W. Spicer, Itchen Abbas, Alresford. 



The membrane must, of course, be mounted in 

 balsam. 



Genera and Species of Diatoms. — At the 

 meeting of the Quekett Microscopical Club, held 

 February 22nd, an interesting communication was 

 read from Mr. E. Kitton, of Norwich, on the con- 

 struction of genera and species upon insufficient 

 data. The illustrations and application of the re- 

 marks were chiefly confined to the Diatomacese ; and 

 the writer contended that it was very unwise to 

 accept a single specimen, or a portion of a frustule, 

 as a type, and constitute thereupon a new species 

 or new genus. Instances were quoted in which this 

 course had been adopted, to the great confusion of 

 the student ; and he further affirmed that it would 

 be better to throw such unique or imperfect speci- 

 mens into the fire, and not attempt to name a new 

 form as a distinct species until a good gathering had 

 been made. In further confirmation of his views, 

 he adverted to the variation in contour of well- 

 known forms, derived from different localities, and 

 the difference in the markings, or striae, in the 

 secondary layer of the silicious shields, which had 

 on some occasions been accepted as distinct species. 

 The tendency had been greatly to multiply both 

 species and genera of Diatoms, without regard to 

 the mutability of form, resulting from the influence 

 of external conditions, and consequently, to create 

 almost inextricable confusion by a formidable array 

 of synonyms. The limits of species and genera 

 have of late attracted so much attention, that 

 the subject of the above paper acquired thereby 

 additional interest. 



