1 INTRODUCTION. 



'pin-pointed', i.e. the upper half of the pin much finer than the lower half. When square 

 cover-glasses are used, the cement is simply painted on with a brush. 



Fig. 22 shows a turntable invented by Mr. Dunning. It is so made that any non-central 

 position may be obtained, even with slides two inches in width, thus facilitating the appli- 

 cation of the cement to any slide the cover-glass of which has not been accurately centred. 



I. METHODS FOR PREPARATIONS MOUNTED IN DAMMAR. 



It is not necessary to apply any cement ; but the preparation looks neater if a ring of the 

 ordinary dammar mounting fluid is run round the margin of the cover-glass. After using 

 the brush wash it in benzole to remove the dammar. 



II. FOR PREPARATIONS MOUNTED IN GLYCERINE OR FARRANT'S SOLUTION. 



After removing all the surplus mounting fluid, paint a ring of marine glue or painter s gold- 

 size round the cover-glass, so as to fix it down, and after it dries (twenty-four hours) put on a 

 thick ring of zinc-wliite cement. It may be necessary to put on more than one ring of zinc 

 cement. This is by far the best way of sealing up these preparations. When the zinc-white 

 dries it forms a ring as hard as enamel. The brush used for the zinc-white ought to be 

 washed at once in benzole, and the one used for gold-size in turpentine, and the one for glue 

 in water. These simple precautions ought never to be neglected. 



Various other substances, as asphalt and melted paraffine are recommended for sealing up 

 preparations, but none of them are equal to the above described method. 



The aesthetically inclined student can easily tint the white cement by adding to it a little 

 solid eosin or any other dye. It is, however, quite unnecessary to spend time in adorning the 

 outer surface of preparations. 



FLUIDS FOR SEALING UP PREPARATIONS. 



1. The ordinary dammar solution may be used. 



2. Zinc-white Cement. (Gum dammar, 8 oz. ; zinc oxide, i oz. ; benzole, 8 oz. Dissolve 

 the dammar in the benzole and add the zinc oxide, and then strain through muslin.) 



3. Marine Glue (Hollis'). 



4. Painter's Gold Size. 



Number 3 or 4 is applied first, and when it becomes dry it is covered with a ring of zinc- 

 white cement. In my opinion gold size is preferable to marine glue. It is not so liable to 

 crack. 



METHODS OF INJECTING THE BLOOD-VESSELS. 



The ordinary method of hardening tissues in chromic acid does not suffice to reveal the 

 arrangement of the blood-vessels of a part, hence we must have recourse to filling the blood- 

 or lymph-vessels artificially with a coloured mass. The coloured fluids at present employed 

 are of two kinds one kind which \& fluid, the other which is solid at ordinary temperatures. 

 The chief medium of the former is water or water and glycerine, and of the latter gelatine. 



