THE PRESERVATION OF MICROSCOPIC SPECIMENS. 287 



exclusively for a long time. Frey, on the other hand, recommends 

 that the final sealing should be made with the cement of Ziegler, 

 above mentioned. 



Finally, for labelling the preparations and the whole arrange- 

 ment of the collection, the shape and size of the slide itself 

 are not quite without importance. In this respect the convenient 

 and pretty design, which Bourgogne, of Paris, has chosen for 

 his well-known preparations (Fig. 162), might be adopted as a 



FIG. 162. 



model. It is similar to that which has been introduced in English 

 collections slides of 72 mm. in length by 24 mm. in breadth 

 (3 in. by 1 in.). The model proposed by the " Exchange Society " 

 of Giessen (48 mm. by 28 mm.) is, in our opinion, unsightly and 

 less convenient. 



For the description of the preparation two labels are usually 

 employed : one upon the left side of the slide with the name of 

 the object, the other upon the right with the number of the 

 collection, or similar notes. If it is of importance to find readily 

 a particular portion in the preparation again, a space must of 

 course be left for registering it. For this purpose, so-called finders 

 have been constructed, yet Hoffman's suggestion still remains the 

 most simple and serviceable, viz., to cut two crosses on each side 

 of the opening in the object-stage, and draw two equal crosses 

 upon the slide exactly over them, after the object has been adjusted 

 in the middle of the field of view. 



Microscopic preparations should be preserved in wood or card- 

 board boxes, the sides of which are provided with grooves in which 

 the slides are inserted separately. To prevent the preparations 

 from gravitating out of position on the slides, these boxes should 

 be placed so that the slides lie horizontally. The slides may also 

 be arranged to lie flat in shallow drawers or trays, which can 

 either be drawn out, as in a cabinet, or lifted out one after another ; 

 they are thus very convenient for inspection. 



