70 PREPARATION AND MOUNTING 



must be allowed to remain in turpentine at least for some cfayp. 

 The turpentine should then be renewed and the eye well washed 

 in it just before it is to be mounted. It may then be set in bal- 

 sam in the same way as any other object; but here a difficulty 

 is met with. The eye being spherical upon the surface required, 

 must necessarily be " folded " or broken in attempting to flatten it. 

 This difficulty may be often overcome by cutting a number of 

 slits round the edges; but some object to this mode of treatment, 

 and where it is practicable it is much more satisfactory to mount 

 one in the natural rounded form and another flat. Instead, how- 

 ever, of mounting the organ whole, four or five slides may be pro- 

 cured from each of the larger ones, as those of the Dragon-fly, 

 &c. 



The antennae also are often mounted on separate slides, as being 

 better suited for higher powers and more minute examination than 

 when connected with the insect. These two projecting organs, 

 issuing from the head, are jointed, and moveable at will. They 

 differ very much in form amongst the various species, and are well 

 worth the attention of the microscopist. They are usually mount- 

 ed with the head attached, and perhaps they are more interest- 

 ing when thus seen. Some few are very opaque, to prepare which 

 the following method has been advised : 



Bleach the antennae by soaking in the following solution for a 

 day or two : 



Hydrochloric acid, 10 drops. 

 Chlorate of potash, J drachm. 

 Water, 1 oz. 



This will render them transparent. Wash well, dry, and mount 

 in Canada balsam. Instead of the above, a weak solution of 

 chloride of lime may be used, by which means the nerves will be 

 well shown. Many, however, are rendered transparent enough by 

 simply soaking in turpentine for a longer or shorter time. Where 

 the antennae, however, are "plumose," or feather-like, extreme 

 care is required in mounting, though the difficulty is not so great 

 as some seem to think. If they are first dried with gentle pres- 

 sure, and then subjected to the action of the air-pump in a small 



