32 DIATOMAi 



contact with the drop. As soon as a few diatoms have ran out 

 of the dip-tube, it is removed. Then a small splinter of wood 

 or stiff bristle is used to disseminate the diatoms through the 

 drop of water in such a way that they will be pretty evenly dis- 

 tributed and not overlie each other. The water is then driven 

 off by heat, a drop of thin Canada balsam placed upon the dry 

 diatoms, and a cover placed on them in the usual manner. In 

 many cases, especially when dealing with the smaller forms, it 

 will be found desirable to mount them upon the cover in this 

 same way, instead of upon the slide, as they will then be 

 brought as near as possible to the objective of the microscope. 

 Single or remarkable specimens of diatoms may be picked out 

 and mounted by themselves; but the manner of accomplishing 

 this would occupy more space than it has been thought desirable 

 to devote to this portion of our subject, and the reader is 

 referred to the books on mounting microscopic objects for the 

 particulars of the process. 



The main principles of preparing and mounting diatoinaceae 

 for preservation and study have been given, and the intending 

 student will be able to devise modifications and improvements 

 for himself, so that he will be able to put up specimens in as 

 finished a manner as any to be procured from the dealers. 



