^60 MICROSCOPIC OBJECTS. 



inftisions, the feeding-pin should be washed in distilled 

 water between each dip, to prevent any mixing. This 

 little contrivance will be found more effective and usefiil 

 than the pomt of a quill or a camel's hair brush. 



(9.) A very amusing exhibition of animalcules is made 

 in the following manner. It is especially calculated for 

 the solar or gas microscope, or indeed any other where 

 the objects themselves are not under immediate inspec- 

 tion. The main feature is the apparent control of the 

 exhibitor over the actions of these minute beings, and 

 their obeymg his commands. Procure a water-trough, 

 similar to the one here represented, composed of two 



b 



shps of glass cemented on each side of a plate of 

 metal of the proper thickness, and of the form 

 shown in the figure, the light part being that which is 

 removed. If it is now filled with clean water and the 

 middle cell, a, placed before the microscope, and a drop 

 of the infusion containing the animalcules put into the 

 cell b, on command of the exhibitor the animalcules will 

 commence marching across the field of view, and to those 

 unacquainted with the plan it will appear in obedience to 

 the order, but is in reality merely for the purpose of 

 spreading themselves. In the same manner when the 

 cell a is full, c may be put under the instrument, and the 

 marching again commences, the little animals not being 

 able to pass from one cell to the other singly. 



t 



