48 Transactions of the Boyal Microscopical Society. 
quarter inch included, Tolies’, and a series of Zeiss’ from the one- 
eighth to the one-twentieth inch. I find that a power of about 
(JOO diameters is requisite to separate the markings sufficiently, 
and that with a power of 1000 diameters they become quite visible 
to anyone, even on the finest specimens, some of which have 
resisted all efforts on the part of some of the best manipulators to 
resolve them. I also find a Boss’s Kelner C eye-piece very useful 
for this purpose, as it gives plenty of light. 
Mr. Wenham’s ingenious reflex illuminator, whether if used for 
the purpose it was originally constructed, viz. for dark ground, or 
whether if put to what one might call its illegitimate use, viz. 
for light ground, becomes therefore one of the most powerful 
means of resolving lined tests mounted in balsam. 
