334 The MrcaoscoPE. 



this country and in England. On the continent of Europe, and 

 by certain microscopists in our own land, there is a smaller size 

 in use. These are about two inches long by half an inch in 

 width. The standard slips are the best and the most satisfac- 

 tory. They are more easily handled, they are pleasanter t© 

 handle, and they look better when the mount is finished. In 

 addition to these reasons, cabinets to hold the mounts are made 

 for standard slides, and, a still more important consideration, 

 by their use uniformity is attained. This the reader will find 

 of especial interest when he comes to exchange some of his 

 preparations for those of other microscopists, as is often done. 

 He would not be pleased to send a fineW-mounted slide of the 

 standard size, and to receive in exchange one of the little Ger- 

 man mounts, that should rattle about in his cabinet to the detri- 

 ment of his collection and to the anno3^ance of himself. 



Tiie I'eader will be wise, then, if he begin his mounting career 

 with the selection of slips of the standard size. These should 

 be of tlie best and the whitest glass obtainable. They may be 

 cut bj'^ the microscopist himself, if he have a diamond and the 

 necessary patience, or he may have it done cheaply ; but slips 

 of the proper kind can be had at so reasonable a rate from the 

 regular dealers tliat it is a waste of time, and usuall}^ of mate- 

 rial as well, to attempt to cut slips at home. And these home- 

 made productions will have rough and sharp edges, as the 

 microscopist will soon discover, for tlie sharp edge of the glass 

 is very sharp, and the little cuts they make in one's fingers are 

 likely to make themselves painfully prominent. The slips to be 

 had from the dealers are of the best and the whitest of crown 

 glass, they are perfectly smooth and free from scratches, striae 

 and other imperfections (or if they are not they should be 

 rejected), and they all have smooth and in some cases polished 

 edges. The beginner should select these rather than attempt to 

 cut them for himself. They should always be perfectl}- flat, as 

 the}' usually are, but, to be sure of this, press two of them 

 togetlier by the broad surfaces. They should be so flat and so 

 smooth that the pressure of the air shall hold them together 

 when they are reversed and turned about in various directions. 

 They are also usually free from imperfections ; all that are not 

 so should be rejected. 



They are obtainable in several thicknesses — the thick, the 



