THE MICROSCOPE AND ITS PARTS. 33 



rent, or drop by drop; and he can allow a drop to en- 

 ter or a drop to flow slowly out at his will. Some 

 workers prefer a tube with a hollow rubber-bulb at- 

 tached, by which the water and contained objects are 

 drawn up by the expanding ball, and forced out by its 

 compression. The writer is prepossessed in favor of 

 the simple tube, as it is less complicated, more easily 

 cleaned, and its- contents are more completely under 

 control. 



To use it, place the tip of the forefinger firmly over 

 upper end, and dip the lower into the water above and 

 near the object desired: lift the finger, and the water 

 will rush in until it is level with that on the outside; 

 close the upper end again, remove the tube, and the 

 water will remain in place as long as the finger stops 

 the upper opening; remove t-he finger and the water 

 will at once flow out. By the proper regulation of the 

 pressure and of the finger movements, the water can 

 be made to escape drop by drop, or in a sudden rush. 

 In this way any small aquatic object can be easily 

 transferred to the slip, and as readily washed off by a 

 sudden outward flow from a full tube. If the object 

 descends too slowly, rotating the tube will hasten it. 



Until recently I supposed this little affair was com- 

 mon property, and that the principle on which it acts 

 was understood by everybody. But when I called on 

 a gentleman, a member of a scientific society, to ob- 

 tain some water in which certain plants were growing, 

 he' expressed surprise at the performance, and called 

 his wife to witness a new and curious method of taking 

 up water with nothing but a glass tube and one finger. 

 His astonishment was amusing; but how much more so 

 was that of a druggist who had a teaspoonful of de- 



