CHAPTER VI. 



ON PEOCURING OBJECTS FOR THE MICROSCOPE. 



THE topic suggested by the title of this chapter is almost 

 endless; for the microscopist may claim contributions from 

 every department of natural science. The animal, vegetable, 

 and mineral kingdoms, all offer him interesting objects of in- 

 vestigation. We shall content ourselves with noticing some of 

 the most important or attractive in each department. 



INORGANIC. 



Agate. This form of silica is often found imperfectly crys- 

 tallized, and thin plates, prepared by the lapidary's wheel, ^th 

 of an inch thick, exhibit a rich motley coloring when viewed 

 by polarized light. 



Carbonate of Lime. Small spherules of this substance are 

 sometimes found in the urinary deposits of the horse. They 

 are often composed of concentric layers; at other times the 

 fibres are radial. Illuminated by polarized light under a power 

 of 100 diameters, they are splendid objects. 



Crystallization of Salts. Independently of the beautiful 

 forms assumed by different salts during their crystallization, a 

 great variety of forms may be obtained by mixing small quan- 

 tities of the different solutions in a little weak gelatine, starch, 

 mucus, &c. To procure specimens, put a drop or two of water, 



