ZOOLOGY AND BOTANY, MICROSCOPY, ETO. 737 



objects from air before mounting in glycerine jelly, depending on the 

 great solubility of air in water : — 



A wide-mouthed bottle, of about four ounces capacity, with a 

 closely fitting solid stopper, is completely filled witb water, which at 

 the time is, and for half an hour previously has been, boiling in order 

 to expel all traces of dissolved air= The stopper being then inserted 

 without inclosing a single air-bubble, the bottle is set aside until 

 cool enough to receive the sections which are then to be put into it. 

 A few drops of boiling water are then to be added to make good the 

 inevitable loss in removing the stopper; the bottle is to be again 

 closed, wiped dry, and securely sealed with melted paraffin. After 

 twelve hours it may be opened, and the whole contents turned into a 

 white porcelain shallow dish. The sections can then be easily seen, 

 and picked out with a section-lifter, and should be soaked for half an 

 hour in a 50 per cent, solution of glycerine before mounting. 



Making Cells of Thin Glass.*— Dr. H. T. Whittell considers that 

 Dr. Beale's plan of making rings by fastening a cover-glass on a metal 

 ring with melted marine glue, and afterwards knocking out the centre 

 with the end of a file, remelting the glue to loosen the ring, and after- 

 wards clearing it off, is a troublesome, time-taking process, and, after 

 experiment, finds that thick gum mucilage may be substituted for the 

 marine glue, and that the cells can then be made with great ease. 



Take any number of the thicker glass rings or squares used for 

 making microscopical cells, fasten on each a piece of cover-glass by 

 means of gum mucilage, let them stand in a warm place for 24 to 48 

 hours till the gum is firmly set. After this break out the centres as 

 in Dr. Beale's method ; the part of the thin glass fastened to the rings 

 will remain intact. It is well, as a precaution, to scratch round the 

 inside of the ring with a writing diamond before knocking out the 

 centre. If desired, the inside edge of the ring may now be smoothed 

 with a fine file ; but he believes the ragged edges are an advantage in 

 giving greater firmness to the adhesion of the glass in its after uses. 

 The centres being cleared, the whole are thrown into water and left 

 there for a few hours, after which, the gum being dissolved, the thin 

 glass rings will be found loose, clean, and ready for use. The be- 

 ginner will probably break a few pieces before he acquires the knack 

 of clearing the centres, but after a little practice nine out of twelve 

 will remain perfect. Thick rings with broad edges will be found 

 best to commence with. 



Dry Mounting. t — Prof. A. H. Chester, at the Chicago meeting of 

 the American Society of Microscopists, read the following paper : — 



" The great difficulty in successfully mounting objects dry has been 

 the deposit on the under side of the cover-glass which is apt to appear 

 sooner or later, and which often so obscures the view of the specimen 

 as to render it comparatively useless. At the Montreal meeting of 

 the American Association for the Advancement of Science, last year, 



* Joura. Quek. Micr. Club, i. (1883) p. 193. 



t ' Chicago Times,' 9th August, 1883, in advance of Proc. Amer, Soc. IMicr., 

 6lh Ann. Meeting, 1883. 



