262 THE AMERICAN MONTHLY [Sep 



ches high, and will cost about 75 cts. The lamp is a small 

 glass methylated spirit lamp, with a glass top, such as is 

 usrd ia laboratories to go beueath the table. This can be 

 purchased for 25 cents. 



Balsam. — The actual process of mounting in Canada 

 balsam may be carried out as follows. We will assume 

 that the object has received a final soaking in turpentine. 

 Having carefully cleaned both slip and cover-glass, the 

 latter in taken up in a pair of forceps, and, the slide hav- 

 ing been breathed upon to slightly moisten it, the cover- 

 glass is placed on the slide and pressed there to make it 

 stay in position. The slide is then placed on the table 

 and the lamp lighted and put beneath. In less than half 

 a minute the plate will be sufiSciently warm — the heat 

 should be no greater tlian will allow of the finger being 

 placed on the end of the slide. A drop or two of balsam 

 is then placed on the cover-glass which is on the slide, 

 care being taken that it does not overrun the margin of 

 the former. Into this the object is then lowered or slid 

 by means of a section-lifter (a cover-glass held in a pair 

 of forceps may serve) and a needle set in a handle. Care 

 should be taken to get the object right down under the 

 balsam and close to the cover-glass. The object should 

 then be examined with a pocket-lens to make sure that its 

 position is satisfactory, and to see that no air bubbles are 

 visible in or around it. It is then placed under a watch- 

 glass or other cover to protect it from dust, and put aside 

 for twelve liours to harden. It will be found that the bal- 

 sam skins over very rapidly on exposure to the air, and no 

 time, therefore, must be lost. The warming of the slide 

 partly obviates this. 



After hardening for twelve hours it is as well to make 

 an examination under the lowest power of the microscope 

 before proceeding further, to make gure that the object 

 itself is properly in position and free from air-bubbles or 

 contained air. The slide is then again placed on the mount- 



