H. T. WHITTELL ON MOUNTING IN GLYCERINE. 193 



dissected for study the viscera of a blow-fly, and I found on my 

 slide all the parts, from stomach to termination of intestine, the 

 kidney tubes, liver tubes, oviduct, and several ova, all well dis- 

 played in situ — an object worth preserving. I knew that the 

 slightest movement would disarrange the specimen, and pressure 

 would ruin it. The ova and lower part of the intestine are rather 

 thick objects for mounting without a cell, but the chalk cement filled 

 up the angles between the cover and slide so effectively that I had 

 no trouble in obtaining a firm and permanent specimen for my 

 cabinet. 



When I was in London I wished to mount some Polyzoa in cells 

 made from rings of thin cover glass, but was unable to purchase 

 such rings except at a price which was prohibitory to their use in 

 large quantities. I was told the trouble of making them was so 

 great that it would not pay to sell them at lower rates. 



Dr. Beale's plan of making these 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 afterwards cleaning it off, is a troublesome 

 time-taking process. After experiment, I find 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 from 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 I believe 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 beginner 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 com- 

 mence with. 



