PLATE 8. 



Proboscis of Blow-fly. 



These two photomicrographs, together with those reproduced on 

 Plate 9, are given to illustrate the wide range of magnification 

 obtainable with a very small battery of lenses. 



Objectives of 1" and 3" focal length and No. 3 eye-piece only were 

 used, with extensions varying from 5" to 20". 



A B 



Magnification ... 15. 35. 



Objective Swift's I" Achromat. 



Eye-piece None. Swift's No. 3. 



Extension ... 15" (from objective). 5" (from eye-piece). 

 Condense?" ... Watson's Universal Achromatic, with 



front lens removed. 



Illuminant ... Incandescent gas. 



Light Filter ... Saturated solution of copper acetate. 



Plate Imperial Special Rapid Ortho. 



Photos. W. B. R. 



To follow page 80. 



