246 THE AMERICAN MONTHLY [November, 



needles are prepared — and some descriptions will be found of great ser- 

 vice later on — they may be coated with gold by shaking up an aqueous 

 solution of chloride of gold with sulphuric ether, which, taking up the 

 gold from the solution, will deposit it on any steel which comes in con- 

 tact with it. When the needles are broad and flat, such as are used by 

 surgeons, they may be mounted in a handle, ground and sharpened, 

 highly polished, and gilded with this solution, they then form excellent 

 scalpels for the minute dissection of insects, and the gold coating pre- 

 vents their contracting rust, which, catching in the delicate fibres of a 

 partly dissected insect, would spoil several hours' work. 



Wash Bottle. — This is a very useful appliance in many microscop- 

 ical operations ; it is readily made by taking a wide mouthed well- 

 corked four-ounce bottle, then perforate the cork in two places, pushing 

 through two tightly fitting glass tubes ; the one reaching to^ the bottom 

 of the bottle may be softened at a point just above the cork by holding 

 it in the flame of a spirit lamp, and bent to an acute angle of 70°, its 

 outer end melted and drawn to a point which may be chipped off' ac- 

 cording to the dimensions of the exit required. The second tube, which 

 will constitute the mouth-piece, may be pushed only just through the 

 cork, and its outer part bent to an obtuse angle of 120°. By partly fill- 

 ing this bottle with distilled water and blowing through the mouth- 

 piece, the pressure of the air on the surface of the water forces it 

 through the other tube, and it may be directed in a fine stream, but 

 with considerable force, against any section or other substance it is de- 

 sii'able to wash. Similar bottles may be made to hold glycerine, salt 

 solution, or any of the mounting fluids to be treated of later on. 



Watch Glasses. — The student is recommended to get about half a 

 dozen of these ; they are used for soaking specimens in staining fluids 

 and for holding isolated specimens. There are some glass pots having 

 lids about the same size as watch glasses, which are very handy and 

 inexpensive. 



Wine glasses which have become broken from their stems are useful 

 for placing over preparations which may be soaking in spirit or 

 staining fluid, if the operator is called off' or has to leave his work for 

 something, as they ward off' dust and check evaporation. 



Dipping tubes and stirring rods may be obtained of any chemist and 

 cannot be dispensed with. 



It is sometimes necessary in warming slides when mounting in Canada 

 balsam, or in making troughs with marine glue to hold them over a spirit 

 lamp. It is not comfortable to do this at the risk of burnt fingers, and 

 therefore this may be done more safely and easily by holding the slide 

 in a pair of wooden forceps constructed as follows : Take two strips of 

 deal of about equal length and thin them oft' at one end, between the 

 thick ends glue in a small block of wood, and, if necessary, tack the 

 slips to make them more secure. This will be found a useful accessory 

 for this purpose, and moreover the glass is not so likely to fly with the 

 heat as if held with metallic forceps. 



Having furnished himself with these indispensable appliances, the 

 student may proceed to make such simple investigations as his imme- 

 diate surroundings may furnish. The more simple and elementary 

 they are the more sure will be his progress. An examination of such 

 an easily obtainable subject as a drop of saliva will aflbrd very instruc- 



