200 The Microscope. 



Tinpleasant glare to the eyes of the operator. A shallow glass dish 

 containing the object of preparation is placed on the glass plate, 

 and a very satisfactory under illumination is obtained. With the top 

 restored to its position it is then used for mounting purposes, afford- 

 ing an under illuminated and raised rest for the slip on which the 

 object may be better seen and manipulated. Its use will be further 

 described with the processes as detailed. 



Another device as a rest for the slip in mounting may be easily 

 made. To the center of a piece of board 8x8 inches, glue flatwise 

 a block 1x1 Jx3i inches. Paste white paper on the top of the block- 

 Then placing a glass slip on the paper, put six pins or short pieces 

 of wire in the block about the slip, to keep it in place. The pins 

 should not project more than ^^ of an inch. A ring as a guide to 

 the center may be made by placing a nickel in proper position on 

 the paper and marking round it with a pencil. 



PREPAKATION. 



Place the object for a few minutes in alcohol, then transfer to 

 the liquor potassfe contained in one of the miniature section jars, or 

 in a shallow ointment jar. This is done to soften and bleach the 

 hard and opaque parts of the insect. The time required will usually 

 be about one week, though some more delicate kinds require only a 

 few hours, and for these it will be best to reduce the strength of the 

 solution. Some obstinate and dense specimens may require even a 

 month in this process. When the liquor becomes much discolored, 

 put the objects in a fresh supply. 



It is best not to carry the softening and bleaching process any 

 farther than is absolutely necessary, and this can only be learned by 

 experience. The process at the best will often destroy the tracheal 

 system of the insect, which is a most interesting part. It is better 

 to depend upon the subsequent processes for the transparency 

 desired. Some insects do not require the use of liquor potassse. 



In using the mounting and dissecting box, remove the top part 

 and place a shallow glass dish, three or four inches in diameter, on 

 the ground-glass plate. The glass dishes used for watch parts by 

 watch - repairers are veiy convenient. Having water in the dish 

 with pliers remove the insect from the liquor potassse to the water. 

 Adjust the liox in relation to the light so that it may best under 

 illuminate the o]:)ject by reflection from the mirror within the box. 

 All needed magnification of the object may be obtained by using a 

 watch-makers eye-glass. The kind having a spring to pass round 



