MOUNTING INSECTS. 307 



from around the cover-glass with a warm knife, and then moisten a 

 soft tooth-brush with a mixture of equal parts of alcohol and aqua 

 ammonia, and a slight rubbing will clean the slide with very little 

 danger. 



After removing the superfluous balsam and cleaning the slide, 

 finish by spinning a ring around the cover with the cement made from 

 the following formula: 



Gum dammar 75 grains. 



Gum mastic 45 " 



Canada balsam, evaporated to dryuess 45 " 



Chloroform 180 " 



Spirits turpentine 100 " 



Mix and dissolve. 



Method of Preparing Minute Entomostraca, Mites, Spiders, Insects, 

 etc. "The specimens should be killed by adding a few drops of 

 osmic acid to the water; when they fall to the bottom they are to 

 be taken up and placed in alcohol of 30 per cent, from which they 

 are to be transferred to alcohol of 50 per cent, then to cochineal 

 solution in 70 per cent alcohol, then washed repeatedly in 70 per 

 cent alcohol, then placed iu 90 per cent alcohol, and finally in absolute 

 alcohol. Then a small quantity of oil of cloves is poured into the 

 alcohol, and at the line of juncture of the two liquids the specimens 

 become permeated with the oil. They are then to be transferred to 

 clear oil of cloves, and finally when perfectly clear mounted in Canada 

 balsam, or embedded in paraffine and cut into sections. By this 

 method specimens can be obtained with absolutely no shrinking of 

 the protoplasm." (M. M. Hartog, Journ. Royal Microscopical 

 Society, London.) 



Carbolic Acid in Balsam Mounting. Put the living insect into 

 carbolic acid;* this in a few minutest clears the object, rendering it 

 transparent and apparently wholly destitute of viscera, but exhibiting 

 clearly the sexual organs. Drain off the superfluous acid and mount 

 without pressure in moderately thick balsam. The acid does not 

 harden the object, but it remains perfectly flexible for a long time. 

 (C. M. Vorce, Science Gossip, June, 1880, p. 139; also Jour. Roy. 

 Micr. Soc., 1881, 139.) 



Killing and Preserving Insects. Mr. G. W. Vickers approves of 

 Mr. Vorce's method stated above, and describes his own mode of 

 procedure. " Place a drop of the [carbolic] acid (pure crystallized 



* Liquefied crystals. N. K M. 



f Some insects should remain for a day or more. N. N. M. 



