iS 



PRACTICAL HISTOLOGY. 



simple microscopes. The complete form of the compound 

 microscope (Fig. 21) has an objective (O) consisting of 





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FIG. 20. Compound microscope 

 Simplest form. (Deschanel. ) 



FIG. 21. Compound microscope 

 Complete form. (Carpenter. ) 



several lenses superimposed, while the ocular is always 

 composed of two converging lenses, the lower one, termed 

 the field-glass (F F), collecting the rays from O. so as to 



