ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



637 



illuminating"' methods (reflected light, obliquely incident light, and 

 transmitted light, figs. 169-171) can be brought into play and their 

 appropriate effects in defining the boundary lines demonstrated. The 



Fig. JGS. 



suitability of the instrument to solid and fluid bodies ranges between 

 refractive indices of 1*0 and of about 1*7 (the index of the flint-glass 

 prism). 



