PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS. 185 



table, made rather thicker than usual, has a dovetail groove ploughed out 

 across its diameter, in which work two sliding guides A, A, the ends of 

 which are cut and ' sprung/ so as to have a sufficiently firm hold. These 

 guides carry the two clips B, B; one of which is fixed at right angles to 

 its guide, whilst the other is pivoted, in order that it may adjust itself 

 to any irregularity in the form of the slide. When Cement-cells are 

 being made either with this or the ordinary Turn-table, it is convenient 

 to mark the centre of each slide with a dot of ink on its under surface; 

 this may be easily applied in its right place by laying on it a slip of card 

 cut to the regulation size, with a small central perforation; and by so 

 laying down the slide that the dot lies on the centre of the rotating plate, 

 much trouble may afterwards be saved. 



177. Mounting Plate and Water-bath. Whenever heart has to be 

 applied either in the cementing of Cells or in the mounting of Objects, 

 it is desirable that the slide should not be exposed direct to the flame, 

 but that it should be laid upon a surface of regulated temperature. As 

 cementing with Marine Glue or hardened Canada Balsam requires a heat 

 above that of boiling water, it must be supplied by a plate of metal; and 

 the Author's experience leads him to recommend that this should be a 

 piece of iron not less than six inches square and half an inch thick; and 

 that it should be supported, not on legs of its own, but on the ring of a 

 Eetort-stand, so that by raising or lowering the ring, any desired amount 

 of heat may be imparted to it by the lamp or gas-flame beneath. The 

 advantage of a plate of this size ahd thickness consists in the gradational 

 temperature which its different parts afford, and in the slowness of its. 



Slider-Forceps. 



cooling when removed from the lamp. When many cells are being- 

 cemented at once, it is convenient to have two such plates, that one may 

 be cooling while the other is being heated. The Retort-stand also serves 

 for the support of the Water-bath, which affords the heat required for 

 liquefying and mixing the fats employed in the imbedding process ( 189), 

 for melting the glycerine jelly or other media used in mounting, and for 

 a variety of other purposes. A circular-bottomed flat tin vessel, 6 inches 

 in diameter and 2% inches deep, with a handle like that of a saucepan, 

 and two covers, one a flat plate of 8 inches square (its edges guarded by- 

 being turned over wire) for slides to lie upon, having a hole large enough 

 to admit a small bottle of cement or medium, the other fitting the- 

 vessel, but with an opening large enough for a porcelain basin, will 

 answer every purpose. 



178. Slider- Forceps, Spring Clip, and Spring-Press. For holding- 

 slides to which heat is being applied, especially while cementing objects 

 to be ground-down into thin sections, the wooden Slider- Forceps (Fig. 

 127) will be found extremely convenient. This, by its elasticity, affords 

 a secure grasp to a slide of any ordinary thickness, the wooden blades 

 being separated by pressure upon the brass studs; while the lower stud, 

 with the bent piece of brass at the junction of the blades, affords a level 

 support to the forceps, which thus, while resting upon the table, keeps 



