24 NATURAL HISTORY OF ANIMALCULES. 



yellow, field of view. Again, if a good Doublet cannot 

 be procured, single lenses, suitably mounted, as in 

 the new Vertical Microscope, display animalcules ex- 

 ceedingly well; and, when skilfully managed, will 

 afford the possessor many an interesting exhibition, will 

 beguile many a tedious hour, and store his mind with 

 some useful truths. 



