68 HOW TO V/OKK 



supply of water. It is covered with a piece of thin glass, but a small 

 opening is left at one side sufficient to allow a fine thread of silk 

 or cotton to conduct the water from the reservoir to the specimen 

 placed in the centre of the slide. The stratum of fluid containing the 

 living bodies can be obtained of the required thickness by placing 

 hair or pieces of fine glass rod between the thin glass and the 

 slide. In some cases it is necessary to apply warmth, and keep the 

 bodies under examination at a certain temperature for a considerable 

 time. The method of warming the slide is described in another part 

 of this volume. 



