248 THE AMERICAN MONTHLY [November, 



drops of chloroform. The flea being rendered insensible, may be 

 affixed by a minute drop of gum on its side to a white card. By 

 the time the action of the intoxicant has passed oft' the gum will be 

 dry and the drunkard will find herself in a fix, and in her endeavors to 

 walk home will display the action of the legs and oral apparatus. 

 These are but suggestions to direct the ingenious student to devise 

 other ways and means for observing the various parts of living insects. 

 One of the most ingenious as well as the most useful appliances to be 

 used in connection ^vith opaque living objects is a cork cell which is 

 constructed in the following manner : Take a slip of cork such as is em- 

 ployed to pin insects out in museums, cut it to the dimensions of a 

 microscopical slide, then cut an oval hole with slightly tapering sides 

 through its centre, and about one inch by three-quarters of an inch ; 

 place glass slides under and over the cork, interposing a pad of wet 

 blotting paper between the bottom glass and the cork, and bind all to- 

 gether with two elastic rings. Any such small animals as podur^e and 

 congeners kept in these cells in the damp and fed on oatmeal will 

 thrive and multiply besides always being ready for examination when 

 wanted ; thus their life-history maybe traced and their habits watched. 



Mounting Opaque Objects. — The student may be desirous of 

 mounting some opaque objects for future reference and investigation, 

 and, to preserve them, they must be mounted in cells of a suitable 

 depth — microscopical cells are square, oblong, or circular — according 

 to the shape and size of the object to be preserved. If the square, or 

 oblong cell is chosen, slips of glass of a suitable thickness, and rather 

 more than ^ inch in breadth, may be procured from any glazier; with 

 short pieces of this the cells may be built, the slides being affixed to a 

 glass slide with warm marine glue ; when cold the superfluous marine 

 glue may be cleaned away, and the bottom of the cell obscured with a 

 black varnish, such as Brunswick black, or it may be painted with India 

 ink, as it is desirable that no light should be transmitted through the cell 

 in examining opaque objects. When the cell is thus far constructed, it 

 should be set aside to become thoroughly dry, or a most annoying dew 

 settles on the inside of the cover-glass, rendering the object indistinct. 

 The author has often found it useful, in these cases, to leave the cover- 

 glass temporarily fastened down, by tacking it in two or three places 

 with some wax, with which a small quantity of Canada balsam has 

 been incorporated, to make it more adhesive. The cover then is suffi- 

 ciently fastened for safety, at the same time excluding dust, while it can 

 be removed at any time should it requh-e cleaning. This mixture of wax 

 and Canada balsam will be found extremelv useful in many ways later 

 on, and several ounces might be prepared in readiness for future use. 

 In mounting very thin opaque objects, which do not need a cell of any 

 depth, it is sufficient to cover them with a circular glass, and by means of 

 a smooth, round piece of iron or brass rod made hot, to run some of 

 this wax preparation round in the angle formed by the edge of the 

 cover-glass and the slide, when, on touching the cold glass, it sets and 

 seals the edge allow'ing a coating of varnish to be immediately placed on, 

 for greater security and permanence, without the danger of its running 

 in and spoiling the object. 



Subjects requiring but a slight addition of depth beyond that suffi- 

 cient for the last class of objects, may be mounted in a varnish cell. 



