"ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 539 



" In view of its early brilliant promise, and present measure of 

 success, would it not be well to try still further to rear it into full 

 maturity ? I now have about two clozen cells over a year old which 

 are as good as when put up — not a flaw or sign whatever of moisture 

 or condensation on the cover — no cracking, or cleaving from the 

 slide. I have also sent at least three times as many to correspondents, 

 mounted in the same way and at the same time, and as yet I have to 

 hear of any going astray. 



I do not know that there is anything essentially new in my method, 

 or anything that others have not done ; still one or two points I have 

 not seen mentioned. 



1st. I try to make the cell perfectly dry. This I do by melting 

 the waos as I make the cell, also by drying the object and cover- glass 

 and mounting as quickly as possible. 



2nd, I hermetically seal the cell. 



Concerning the first, I melt the wax as it is put on the slide, and 

 also again as I shape it with the glass rod. I consider the melting as 

 a very essential step in the process, as will be seen by the " sputtering " 

 when melted and when remelted by the glass rod. The sputtering 

 indicates moisture. The details are as follows : — 



For deep cells I use brass rings to suit f-inch covers ; for shallow 

 cells one or two layers of tin-foil rings cut out with gun-punches. 

 First cut from thin wax sheets two or three disks, and place on the 

 slide — on the discs, place the ring (heated). Heat the slide till the 

 wax melts. Some of it will run under the ring and form a wall 

 outside the ring. Press the ring to the slide. Before it solidifies put 

 it on a turntable and centre it. This will necessitate quick work on 

 the non-self-centering table. It is best to prepare a number of slides 

 thus far before the next step is taken. 



The cell is now half or two-thirds full, and level. Next take a 

 glass rod 6 or 8 inches long and f inch in diameter, round one end off 

 in an alcohol flame, heat it hot enough to melt wax, and with the slide 

 on the turntable make a depression all round the cell next the ring. 

 This remelting and stirring as the table revolves, has the efi"ect to 

 still further displace any remaining air. Keep the table revolving 

 until the rod is cold and the wax solid. The cell has now a raised 

 ridge of wax on and at the inner edge of the ring, and a raised central 

 part on which the object is to be mounted. (Fig. 130.) 



Fig. 130, Fig. 131. 



(f ' f 



Vertical section of cell, a a, cross Bevelled turning tool, actual width at 



section of ring ; b, central portion. point ^% inch. 



Now with a turning tool (Fig. 131) made on the end of a small thin 

 flat file or a similar piece of metal, turn the cell down as in Fig. 132. If 

 the form of the object to be mounted permits, it can be fastened in 



