PREPARATION AND MOUNTING 71 



in opaque cells which were made by blackening the 

 cell bottoms ; but this custom is now abandoned. 

 If objects need a black background it can be 

 supplied by placing a sUp covered with dead-black 

 paper under the slide on the stage of the microscope. 



The foregoing instructions apply only to opaque 

 objects that can be mounted dry ; some need to be 

 mounted in fluids. But such work is not likely to 

 be tackled by the beginner. 



It ought to be mentioned that aU objects for the 

 microscope should be reduced to the smallest possible 

 proportions. I remember an individual who put 

 a chunk of cheese under his microscope in order to 



Fig. 24. — Balsam Bottle, with Dipping-Rod. 



examine cheese mites, and wondered that he was 

 defeated in his purpose. A thick mass of pollen 

 grains in a cell is useless ; a few grains spread over 

 the cell bottom are all that is necessary. It is also 

 desirable that objects be mounted as flat as possible, 

 so that they appear in one plane. 



The next step is to mount transparent objects, 

 which are to be examined by transmitted light, in 

 Canada balsam. For this work we shall require : 



1. A stock of Canada balsam dissolved in benzole. 

 A Is. bottle will suffice to begin with. 

 ' 2. A balsam bottle. This is a wide-mouthed 

 bottle with a glass cover cap (Fig. 24). 



