ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 509 



its being clamped to the table M'. The two parallel parts BB, 

 which are of the same 1-2 in. mahogany, stand about 1^ in. apart ; 

 they are 4 in. long, and, rising to 1 in. high, each carries on the upper 

 surface a piece of quarter-in. plate glass CO, of the same length and 

 breadth as itself. This is to support and steady the knife as it is 

 pushed across the tissue to be cut, while the fact of the tissue coming 

 up between the plates allows that part of the knife which is to cut 

 the specimen to be kept free of contact until it touches the tissue. 



The method of raising the section plate H is as follows : — About 

 2 in. of accurately fitting double brass tubing are taken, and into the 

 outer one D the nut F of a fine screw is firmly soldered at what is 

 to be its lower end. The inner tube E has the section plate fixed 

 to its upper end by two screws, with, however, two small pieces of 

 vulcanite intervening between the plate and the tube, so as to dis- 

 connect them as much as possible, and into the lower end of the inner 

 tube a transverse bar is fitted, against which the screw coming through 

 the outer tube presses when it is desired to raise the section plate to 

 which the inner tube is attached. By means of a small screw-nail 

 fixing the outer screw to the bar in question, the inner tube can be 

 withdrawn, as well as pushed up whenever that movement is required. 

 A milled head G has been substituted for the ordinary capstan arms, 

 for turning the main screw round. 



The spray points are introduced at the requisite distance below 

 the section plate by cutting a narrow slot through both tubes, and 

 fixing to the inner one a piece of bent brass, into which the spray 

 points can be pushed and held firmly, vp^hile a small shoulder on the 

 latter prevents them from passing beyond the centre of the under 

 surface of the plate. 



Finally, the ether bottle J (with the tubes K and L) is fastened to 

 the side of one of the upright pieces of the framework by a simple 

 hook and eye, the hook being fixed to a collar round the neck of the 

 ether bottle, and the eye to the side of the framework in question. It 

 will be seen, I think, from this description, that with the exception 

 of the fine screw for raising the tissue, the details of the mechanism 

 are very simple, hence the low price at which it can be sold ; and in 

 practice it has been found to work admirably." 



The instrument is to be obtained from Mr. C. Coppock. 



Glycerine Mounting.* — For vegetable sections glycerine is one 

 of the best preservatives, but the difficulty of confining it within the 

 cell has been deemed insuperable. A method invented by Professor 

 Hillhouse enables this end, it is said, to be perfectly attained. The 

 mode of operation is as follows : — 



No cell is used, the object being merely placed in a drop of glyce- 

 rine of sufficient size to reach the edge of the cover-glass when it is 

 dropped in. Canada balsam, dissolved in turpentine, is then applied 

 round the edge so as to close the cell, by means of a small glass rod 

 drawn out to a point, but terminating in a little knob. If a little of 

 the glycerine should exude beyond the cover-glass, it need not be 



* Midi. Natural., vi. (188.3) p. 166. 



