Chapter XIII : Objects of General Interest 93 



4. Lay the leg, disk side uppermost, in a drop of balsam on a slide, 

 add another drop of balsam and carefully cover with a clean cover-glass. 

 Place a small weight (e. g., half of a bullet) on top of the cover to hold 

 it down until the balsam hardens. 



VI. DRY MOUNTS 



A. Scales. Prepare a very shallow cell and let it dry. Thoroughly 

 dry the scales from a moth's wing by gently heating them on a slide 

 over a flame. Place the scales in a cell, warm the slide until the cell 

 wall becomes sticky, put on the cover and press it down until it adheres 

 all around, and finally seal as in previous exercises. 



B. Eggs of Butterflies, Small Feathers, Antennae of Insects, etc., may be 

 mounted as dry objects. Care must be taken to have them perfectly 

 dry, or they will in time cloud the cover with moisture from within. 



MEMORANDA 



1. Small or Soft Insects or Their Larvae may frequently be mounted 

 directly in glycerin, or they may be dehydrated and mounted in balsam. 

 A method often used is to kill them in strong carbolic acid and mount 

 them directly in balsam. The carbolic acid both dehydrates and clears. 

 It is better, however, to clear the preparation further by immersion in 

 cedar oil or xylol before adding the balsam. 



2. Insects Having Hard Shells must first be soaked in 10 per cent, pot- 

 ash to soften them and render them transparent if they are to be exam- 

 ined by transmitted light. The softer parts of insects so treated are 

 destroyed and only the external parts remain. Such insects may be 

 mounted in glycerin or glycerin-jelly, or they may be dehydrated, 

 cleared and mounted in balsam. 



3. Delicate Insects, which are too frail to withstand much handling, 

 may be placed at once in cedar oil or turpentine and after an hour 

 mounted in balsam. 



4. Wings, Legs, Antennae, Mouth-Parts, etc., of Such Forms as Flies and 

 Bees which have been preserved in alcohol, should be completely dehy- 

 drated, cleared and mounted in balsam in cells of the proper depth. 



5. Transparent and Soft Insects may be stained in borax-carmine or 

 hematoxylin in the ordinary way and mounted as whole objects, if 

 desired. They will stain better if they have been fixed previously in 

 some corrosive sublimate mixture and then washed properly (see Appen- 

 dix B, reagent 13). To stain, follow the method outlined in IV, A. 



6. To Center an Object in a Cell (the head of an insect, for example),, 

 thread a fine needle with a hair and run it through the object. Remove 

 the needle and imbed the ends of the hair in the cement on opposite 

 sides of the cell. When the cover-glass is put in place the object may be 



