DIPPING TUBES. 



191 



object, may be separated by pressing the two projecting 

 studs ; to the opposite end of the wire is adapted a small 

 brass cup, filled with cork, into which pins, passed through 

 discs of cork, card-board, or other material, having objects 

 mounted on them, may be stuck. 



Dipping-tubes are tubes of glass, fig. 114, about nine inches 

 in length, open at both ends, and from one-eighth to one- 



Fig. 114. — Dipping Tubes. 



Fig. 115. 



fourth of an inch in diameter. The ends must be nicely 

 rounded off in the flame of a blow-pipe; some of them may 

 be made perfectly straight, while others should be drawn out 

 to a fine point, and made of either of the shapes a, b, c, d, e. 

 The method of using them is as follows : — Supposing the 

 animalcules are contained in a phial or glass jar (fig. 1 15). 

 and having observed where they are most numerous, — 

 either with the naked eye, or with a pocket-magnifier, — 



