as applied to Photo-micrography. 369 
ones The first, which represents the 6th square of the Mél- 
ers type-plate of the diatomaces, taken with Wales’s 1} incl 
objective, arranged to give thirty-five diameters, will serve for 
comparison with the photographs of the same object with the 
Same lens taken by sunlight and by the electric and magnesium 
ps, which were published with my former report. The sec- 
ond represents the Navicular Lyra, taken with the Powell and 
Lealand’s immersion ;', arranged to magnify 1000 diameters. 
