1890.] MICROSCOPICAL JOURNAL. 247 



tive lessons in the flaky masses of flattened epithelial scales filling the 

 field of view. The immense number of round dark rings are air bub- 

 bles, which once seen in this fluid will be readily recognized whenever 

 met with afterwards. The drop of saliva being placed on the slide, 

 the cover-glass is gently picked up in the forceps by one edge while 

 the opposite side is lowered on to the fluid and allowed to fall by its 

 own weight. All fluid mountings sliould be accomplished in this 

 manner. 



Simple Examinations. — Microscopical subjects may be divided 

 into opaque and transparent, both subdivisions teeming with interest, 

 but requiring diflerent treatment in their examination. The examina- 

 tion of opaque objects requiring less preparation than those of the 

 transparent subdivision may well occupy our consideration in the first 

 place. Having a glass slide on which the opaque object is placed, it 

 is only necessary to throw the rays of light on it with the condensing 

 bull's-eye lens supplied with the microscope and examine it first with 

 the lower power, and when all its general appearance is mastered then 

 using a higher power lens to investigate the detail of its exterior. We 

 are not able in the examination of this class of object to do more than 

 gain a knowledge of its external characters ; nevertheless the student 

 will find abundant material in it to interest and instruct. It may save 

 him trouble and be suggestive, if he commences his observations with 

 such as may be found in the following list, viz., minute animals, such 

 as cheese and other mites {acari), 



Podiircv. — Little silvery animals generally found abundantly in fern 

 cases and amongst moss, or under damp stones or tiles in the garden, 

 where they may often be found in companv with a little light brown 

 pseudo-scorpion called chelifer. In the examination of this class of 

 object it is very necessary to employ a cell. A cell is anything which 

 can imprison and confine, and a microscopical cell may be constructed 

 of any material by which you can form walls either circular or square 

 to be roofed in with a cover-glass, for by this means you are enabled 

 to restrain the peregrinations of your menagerie. If many chelifers 

 are confined together, they will quickly mutilate each other, and even 

 one kept in a cell has been known in its futile rage and despair to tear 

 oft' its own pincers or its legs. As the arachnida to which they be- 

 long include on the one hand the scorpions and on the other the spiders, 

 we may naturally look for something rapacious in their habits, minute 

 as they maybe ; these are but few amongst many instances which might 

 be given, but it will be sufficient to indicate these few as suggesting the 

 line of observation the student may take with advantage. Whole in- 

 sects or parts of them may be submitted to examination. One sugges- 

 tion may be in the direction of looking at the eyes of flies of various 

 kinds, or their mouths or proboscis, and it aftords a very interesting 

 study to imprison a bluebottle fly in a small paper cone, the apex of 

 which has been cut oft' sufficientlv to allow the fly to pass its head and 

 proboscis through, when it is generally fixed, and not easily withdrawn 

 until the cone is undone. This method will exhibit in an interesting 

 manner the working of the proboscis or so-called blowfly's tongue, the 

 contraction and expansion of its disc, showing the horny chisel-shaped 

 teeth which lie on either side just within it. A live flea may 

 be put under a wine glass on some blotting paper with a few 



