112 SPECIFIC EXAMPLES OF SLIDE-MAKING 



the second stender dish, where it may remain about two hours, and then to 

 the third stender dish, where it should not remain for more than one hour. 



Shortly before the end of this last hour, a decision should be made as to 

 what type of vessel is to be used for casting the block. It would be difficult to 

 improve on a paper box (see p. 59) for this object. When the box is made 

 (it should be of ample size), it is moistened at the bottom and placed on a 

 slab of glass in the manner previously described (see p. 60). It should then be 

 filled about halfway with embedding material from the beaker and allowed to 

 remain until about half of this wax has congealed on the bottom. An object 

 like the one under discussion is better handled with old forceps than with a 

 pipette. The forceps should now be warmed in a flame to well above the 

 melting point of the wax and moved backward and forward across the surface 

 to melt the solid film which has formed. Then the object is picked up rapidly 

 from its stender dish, placed in the wax, and enough fresh wax from the beaker 

 added to make sure that there will be as much solid wax above as there is 

 underneath the specimen. Blocks of this nature shrink greatly, and it will prob- 

 ably be best to fill the box entirely. As soon as the box has been filled, the 

 forceps should be warmed again and passed backward and forward around the 

 object to make sure that no film of unmolten wax, which would cause it to 

 cut badly, remains. The wax in its box should now be blown on until it starts 

 to congeal on the surface. Then it is picked up very carefully with the fingers 

 and lowered into a dish of water at room temperature (the water does not 

 quite reach the top of the box). If it is thrust under the surface at this point, 

 all the molten wax will come out, and the block be rendered useless. As soon 

 as the block has congealed throughout, it is thrust under the surface of the 

 water and something is laid on it to keep it at the bottom. It should be left 

 in the water for at least five or six hours or much better, overnight. 



The block should be trimmed so that there is at least as much wax on each 

 side of the object as there is in the object itself This amount of wax would 

 be excessive for serial sections, but for the preparation of individual sections 

 of this type in an example given for the benefit of the beginner, this quantity 

 is desirable. When the microtome is set up and the knife is sharpened in the 

 manner previously described, the block is mounted. This process has been de- 

 scribed in some detail (see p. 64) and need not be repeated here. The block 

 having been trimmed to size and mounted, there remains only the actual cut- 

 ting. The handle of the microtome should now be rotated rapidly and the 

 beginnings of the sections observed. There is no need to worry if the section 

 curls to one side or the other during this preliminary period since the entire 

 thickness of the block will not be cut until 20 or 30 sections have been removed. 



