298 MAJsriPUiATioJsr. 



of the tube, c; if any air bubbles be seen at the bottom of the 

 cell, they should be touched with a sharp pointed instrument, 

 and be conducted by it to the top, where they will burst, and 

 so disappear. The preparation (which we will suppose to be 

 a piece of injected mucous membrane) having been cleaned 

 and soaked for a little time in a similar fluid to that in which 

 it is about to be mounted, must be placed in the cell, and 

 moved about in the fluid, so that all air bubbles may be got 

 rid of, the thin glass cover is then to be placed on, and all the 

 superfluous fluid either drawn away by the sucking- tube, 

 fig. 201, or by the blotting-paper, as previously described, the 

 use of the bulb in the tube being to prevent the fluid from 

 rushing suddenly to the mouth. When both the edges of the 

 cell and cover are dry, a thin layer of one of the cements must 

 be applied to them, this layer should be allowed to get hard 

 before another is laid on ; when much of the cement is used 

 at first, it is apt to run into the cell, which may be avoided by 

 keeping the first layer very thin, and adopting the precaution 

 of letting it harden before the application of the second. In 

 order to give neatness to the appearance of the mounting, the 

 last coating may consist of black or red sealing-wax varnish, 

 or the edges may be covered with bronze powder, or even 

 with gold leaf, both of which wiU adhere if applied before the 

 last layer of cement is quite dry. The object to be mounted 

 and the preservative fluid should be kept as free from particles 

 of dust as possible, and to prevent the admission of these into 

 the fluid, the employment of the bottle shown by fig. 200 is 

 recommended; should, however, some foreign particles have 

 gained entrance, they, in all probability, after a httle time, 

 will sink to the bottom of the bottle, where they will be out 

 of the reach of the end of the tube, if adjusted as represented 

 in the figure. 



To prevent the cement from running into the cell, or the 

 marine-glue from covering more than certain portions of the 

 bottom of the same when fastened to a slide, Mr. Kainey has 

 contrived the following forms. One of these, consisting of a 

 plate of glass about one-eighth of an inch in thickness, and 

 one inch square, with a hole through the centre, is shown by 



