12 MICROSCOPICAL JOURNAL. [January, 



in the eai'wig are six in number, of a circular shape. In the flea they 

 are six in number, but oval. In the bee they are eight in number and 

 elongated. Many interesting points may be made out in the examina- 

 tion of newly-iiatched insects : for instance, the wings of a butterfly 

 are far more beautiful objects if the butterfly is removed from the 

 chrysalis before it has had time to spread its wings. So in the blow-fly 

 freshly hatched, many parts, such as the tongue, can be more easily 

 mounted than after they get old and stifl". A freshly-hatched blow-fly 

 may be fed on cochineal and sugar, when, on dissecting the alimentary 

 canal, it will be found colored with the carmine for its whole track. 



Many beautiful specimens may be made fi"om small insects which 

 have been steeped in the strongest carbolic acid solution, especially if 

 they are mounted entire without compression. Calvert's crystalized 

 carbolic acid, which is solid at ordinary temperatures, is the most suit- 

 able. If this is liquefied by heat, and about one drachm of glycerine 

 added to two ounces of melted carbolic acid, it will prevent its becom- 

 ing solid again. In this condition it is not only useful for rendering 

 insects transparent, but can be used for cleaning all stained vegetable 

 sections instead of oil of cloves. It may sometimes be necessary to 

 bleach insects, especially if they are to be photographed through the 

 microscope. Such a bleach may be made by placing some crystals of 

 chlorate of potash in a wide-mouthed two-ounce bottle, and pouring on 

 one ounce of water ; if to this a few drops of hydrochloric acid be 

 added, chlorine gas is slowly evolved, which, acting on the chitine of 

 the insect's skin, after a week's immersion bleaches it as white as paper. 

 Since it destroys all internal anatomy by its corrosive action, the student 

 must be careful not to inhale the fumes from it, as bronchial mischief 

 may easily ensue. Interesting specimens may be made from the corneae 

 of the larger insects, such as Dytiscus marginalis. They are more 

 easily removed, and are tougher to manipulate. On cutting them off' 

 they will be found convexo-concave in shape, the concavity being filled 

 with pigment, which must be carefully cleansed with a camel's-hair 

 brush. They are difficult to mount on account of their convex form, 

 but by judicious slitting in two or three places round the edge and by 

 pressure they may be flattened sufficiently to show the lenticular struc- 

 ture. If properly prepared, each facet shows clearly any object placed 

 on' the mirror beneath the stage, thus small portraits, the seconds dial 

 of a watch, etc., are reproduced in each lens, and afl'ord much interest. 

 The recent eyes of insects are also interesting as opaque objects, but 

 soon lose their beauty on account of fost mortem changes, which 

 render them black. Opaque objects of rare beauty, like some of the 

 green weevils, may be got by sweeping a bed of nettles with a bag-net 

 of muslin ; these keep their brilliant color for yeafs. They should be 

 mounted in a rather deep glass ring cell, the bottom and sides of which 

 have been painted with a dead black varnish. When this is thoroughly 

 dry, the weevil may then be set upright on its legs, the abdomen being 

 attached to the bottom of the cell by a small portion of the wax and 

 Canada balsam cement. This will form a good and tenacious attach- 

 ment. The legs may be arranged in their natural positions, and the 

 cell covered with a circular glass cover, just tacked in two or three 

 places with the wax and Canada balsam. This will keep the cover 

 safe, and should it become dewed by any exhalation, either from the 



