32 MICROSCOPY FOR BEGINNERS. 



board is fastened to a strip of wood, and a small pin is 

 driven into each corner. "When the ring is made, put 

 the slip in a warm place until the cement is hard, or 

 hold it over the lamp flame for a few moments at a 

 time, taking care not to allow the shellac to boil, or the 

 bubbles will never disappear and the ring will be weak- 

 ened. These lamp-dried rings are hard as soon as cold, 

 and they adhere so firmly that they can only be scraped 

 off with a knife and hard work. They have the further 

 advantage of being rapidly made. 



A deeper and perhaps a somewhat neater cell can be 

 formed from paper. Cut a circular disk, of the diameter 

 of the ring required, from porous paper as thick as the 

 depth of the desired cell, and from the centre cut out a 

 smaller disk, leaving a ring with a narrow rim. Soak this 

 ring in thin shellac cement until its pores are filled with 

 the liquid, and hang it on a pin in a warm place to dry. 

 Several can be prepared at once, and can be of different 

 sizes and thickness. They are fastened to the slip by 

 touching one side with a little shellac and pressing the 

 glass on it and allowing it to dry, or by gently heating 

 the slip and ring over the lamp. It is a good thing to 

 prepare several slips at one time, so as to have them 

 ready for an emergency, as, for instance, after an excel- 

 lent gathering of microscopical material has been made, 

 and the student is so anxious to see what he has that he 

 cannot take time to clean the slide and cover after a 

 hasty glance for rarities, but must have another ready 

 at a moment's notice. 



