THE AMERICAN 
MONTHLY 
MICROSCOPICAL JOURNAL. 
Entered at the post-office as second-class matter. 
VOL. XXIII, JUNE, 1902, NO. 6, 
CONTENTS. 
On the Critical Employment of the Microscope for Ordinary 
emememmiriones,” Merlin... Se eis ds bb weg sale ep cee duces I15-125 
Evolution as seen in Amphiprora. Edwards................. 125-127 
The Chmcn-pog Pungns Garman... ... 0. a ceeees 128-130 
A Simple Form of Monochromatic Illuminator. Edwards.... 130-131 
Method of Feeding Phyllopods and Cladocera, Hertog...... .» 131-132 
NovEs By M. I. Cross.-—-Pond-life Collecting ; Hints on section 
ee os Sale coca kwoeaeedeasas oMsine nen 133-134 __ 
MISCELLANEOUS.--Stebbins ; Gucmnminies WGe i Neds ereluts 134-134 
On the Critical Employment of the Microscope For Ordinary 
Working Purposes. 
A. A. MERYIN, F.R.M.S. 
It is sufficiently evident to the observant visitor at mi- 
crospical exhibitions and soirees that a large number of 
the specimens there shown, although most beautifully 
and carefully prepared and mounted by their exhibitors, 
are optically arranged with a total disregard of the rudi- 
mentary elements of critical microscopy, notwithstand- 
ing the fact that the instruments and accessories actually 
employed could be easily utilized so as to afford more 
satisfactory results. The following causes should per- 
haps be reckoned amongst those principally responsible 
for the existence of this state of things. 
(1) The considerable training and practice required 
to enable the eye to fully grasp the points of difference 
between a critical and non-critical diffraction image, or 
to appreciate the delicately faint, but true, rendering of 
