14 COLLEMBOLA OF MINNESOTA 



give good permanent results. Formerly I used xylol as a clear- 

 ing agent, but found it rather too rapid in evaporation ; so that 

 in mounting a dozen or more insects under one cover, it was 

 difficult to keep some of them from getting too dry before apply- 

 ing the damar. Cedar oil is slower in evaporating, and is there- 

 fore preferable. The colors in the Collembola are generally al- 

 most permanent when in damar mounts, though I think glycer- 

 ine jelly keeps them brighter, and has, besides, the merit of do- 

 ing away with the necessity for clearing. 



When it is desired to destroy the pigment to better study 

 ocelli, post-antennal organs, etc., a drop of a 5^ potash (KOH) 

 solution may be run under the cover glass, and its action arrested 

 by the introduction of alcohol or water when the specimen is 

 clear enough ; after which dehydration and mounting may pro- 

 ceed as usual. For a minute examination of the claws, furcula, 

 etc., of some of the thicker bodied species, it will be found nec- 

 essary to dissect off the parts wished for examination, as the 

 body often makes too thick a mount to allow of focussing with 

 a high power lens. 



