270 PREPARATION OF SECTIONS 



tie a cloth over the dish to keep out the dust and allow the gly- 

 cerine to concentrate by evaporation, and when it appears 

 like undiluted glycerine place the material in a drop of glycerine 

 on a glass slip, put on a coverglass, wipe away all surplus glycerine 

 with a moist cloth, dry the slide thoroughly, and with a turn table 

 (Fig. 146) spin a ring of shellac cementing the coverglass to the 

 slide. To make the shellac cement make a thick solution of 

 ordinary gum shellac in 95 per cent, alcohol and add twenty 

 drops of castor oil to the ounce. 



A more durable preparation is made by mounting in glycerine 

 jelly. To make the jelly, soak one gram, of best gelatine in 

 six grams of distilled water for two hours or so; add seven grams 

 of pure glycerine and 0.15 gram of concentrated carbolic acid; 

 heat this and stir it with a glass rod until it becomes clear; put 

 filter paper into a funnel, run distilled water through it, set it in 

 an incubator or oven just warm enough to keep the jelly fluid, 

 and filter the jelly into a bottle; cork the bottle. For use set 

 the bottle in warm water until the jelly liquefies. To mount 

 material in the jelly warm a slide, put a drop of the liquefied 

 jelly on it and transfer the material from the concentrated gly- 

 cerine to the drop, put on the coverglass and after the jelly 

 stiffens spin the ring of cement. 



