Chapter XIII: Objects of General Interest 95 



11. To Keep Water from Evaporating from a Cell too Freely use a round 

 cell and cover it with a square cover-glass. Apply a brush wet with 

 water to the slide beneath one of the projecting corners of the cover from 

 time to time. Capillary attraction will draw in the water and will keep 

 the cell full. If a continuous supply of fresh water is necessary, one 

 end of a loosely twisted cotton thread may be laid along one side of the 

 cover and the other end of the thread immersed in a small vessel of 

 water which stands within half or three-quarters of an inch of the cell. 

 A reservoir made from the bottom of a shell vial or homeopathic vial 

 answers very well; it may be cemented to the slide. 



Protozoa and other small forms may be kept alive on a slide for a 

 number of hours by simply mounting them in water under a cover in a 

 cell of blotting paper which has been saturated with water. 



12. Deep Cells are made frequently by cutting out rings of paper, 

 lead, or block-tin with gun punches and cementing them to the slide. 

 Glass and hard rubber rings of various sizes may be purchased from 

 dealers. 



