Monthly Microscopical! 
Journal, Feb. 1, 1869. J 
Boyal Microscopical Society. 
93 
imperfect definition, and the surface appears similar to the Gram- 
matophora marina, or P. angulatum ; it is, however, much more 
difiicult to resolve. 
It has been said that objectives which give the best results on 
Nobert's Test-lines and on Test-diatoms necessarily give inferior 
images of Podura scale. It is quite certain that the more powerful 
objectives — those giving greater magnification and definition — 
do not give so flattering an image of Podura scale as is given by a 
good ^th. But the fault, if anywhere, is in the object, not in the 
objective. Podura scale is as fine a Test as any for a ^th, but not 
for the higher powers. 
In conclusion, I would suggest that the Society should improve 
the collection of Test-objects in its possession, and specially that we 
should have one of Nobert's new Test-plates ; so that the Fellows 
may try their objectives on a Standard Test of this kind. 
