192 SELECTION AND tJSE 



cutting, while the one in the left hand is used for holding the 

 object firmly in its place. For the latter purpose, however, we 

 prefer a very narrow spatula, curved and highly polished. 

 Curved needles, with the curve placed flat, answer very well, 

 however. 



For the removal of loose matter, and for arranging parts 

 which have been dissected out, there is nothing more useful 

 than good camel hair pencils. Indeed, they are indispensable, 

 and with needles and pencils two of the simplest and cheapest 

 articles it is possible to do almost everything. 



During the process of dissection the object must be supported 

 upon a glass plate or a dissecting pan, according to its size. Some 

 of the finest preparations have been worked up on ordinary slides 

 three inches long by one wide, and as it is almost always neces- 

 sary to have the object covered with liquid, a single drop suf- 

 fices in this case. But where larger objects are to be dissected, 

 ordinary slides are not large enough, and besides there is no 

 provision made for holding a sufiicient quantity of liquid. 

 Various kinds of dissecting dishes or pans have therefore been 

 devised. Those used by the author are exceedingly simple 

 and cheap, and are shown in Fig. 60. We use three kinds, 

 two with opaque bottoms, and one 

 in which the bottom is transparent. 

 The latter is used for objects which 

 are transparent, and is precisely like 

 the others, except that a portion 

 Fig. 60. of the metal bottom is cut away and 



a piece of plate glass cemented over 



the aperture. Those used for opaque objects are simply 

 oblong tin dishes, each two inches long, one and a quarter 

 wide and half an inch deep. The bottom plate extends on each 

 side, so as to form rests for the fingers, by which the pan may 

 be kept steady. Into this pan is poured a mixture of equal 

 parts of resin and beeswax, softened if necessary with a little 

 lard. It should be just so soft that a 'pin may be easily stuck 

 into it, and this affords us the means of pinning out the different 

 parts of a dissection as we progress. In one dish the wax is 

 colored black with lampblack, and this forms a wonderfully 

 f ffective back ground for most objects; the wax in the other 



