PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS. 



183 



Built-up Cells. 



wall; and a strip is then to be cut off with the diamond from each of its 

 edges, of such breadth as shall leave the interior piece equal its dimen- 

 sions to the cavity of the cell that is desired. This piece being rejected, 

 the four strips are then to be cemented upon the glass slide in their 

 original position, so that the diamond-cuts shall fit together with the most 

 exact precision; and the upper surface is then to be ground flat with emery 

 upon a pewter plate, and left rough. The perfect construction of large 

 deep cells of this kind (Fig. 123, A, B), however, requires a nicety of 

 workmanship which few amateurs possess, and the expenditure of more 

 time than Microscopists generally 



have to spare; and as it is con- rro - KJJ. 



sequently preferable to obtain 

 them ready-made, directions for 

 making them need not be here ^ 

 given. 



175. Wooden Slides for Opaque 

 Objects. Such 'dry' objects as 

 Foraminifera, the capsules of 

 Mosses, parts of Insects, and the 

 like, may be conveniently mounted 

 in a very simple form of wooden 3 

 slide (first devised by the Author 

 and now come into general use), 

 which also serves as a protective 

 'cell.' Let a number of slips 

 of mahogany or cedar be pro- 

 vided, each of the 3-inch by 1-inch size, and of any thickness that may 

 be found convenient, with a corresponding number of slips of card of the 

 same dimensions, and of pieces of dead-black paper rather larger than the 

 aperture of the slide. A piece of this paper being gummed to the middle 

 of the card, and some stiff gum having been previously spread over one side 

 of the wooden slide (care berng taken that there is no superfluity of it 

 immediately around the aperture), this is to be laid down upon the card, 

 and subjected to pressure. l An extremely neat ' cell ' will thus be formed 

 for the reception of the object (Fig. 124), the depth of which will be 

 determined by the thickness of the slide, and the diameter by the size of 

 the perforation; and it will be found convenient to provide slides of 

 various thicknesses, with apertures of different sizes. The cell should 

 always be deep enough for its wall to rise above the object; but, on the 

 other hand, it should not be too deep for its walls to interfere with the 

 oblique incidence of the light upon any object that may be near its 

 periphery. The object, if flat or small, may be attached by Gum-muci- 

 lage ( 168 &); if, however, it be large, and the part of it to be attached 

 have an irregular surface, it is desirable to form a 'bed' to this by gum 

 thickened with starch. If, on the other hand, it should be desired to 

 mount the object edgeways (as when the mouth of a Foraminifer is to be 

 brought into view), the side of the object may be attached with a little 

 gum to the wall of the cell. The complete protection thus given to the 

 Object is the great recommendation of this method. But this is by no 



1 It will be found a very convenient plan to prepare a large number of such 

 Slides at once: and this may be done in a marvellously short time, if the slips of 

 card have been previously cut to the exact size in a bookbinder's press. The 

 slides, when put together, should be placed in pairs, back to back; and every pair 

 should have each of its ends embraced by a Spring-press ' % Fig. 129) until dry. 



