1902 MICROSCOPICAL JOURNAL 85 
ser, which they have submitted to us for examination. 
Its N.A. is 1, and its aplanatic aperture is not less than 
‘95, whilst if the exact thickness of slip for which it is 
corrected be used its total aperture is aplanatic. The pow- 
er is 4-10th of an inch, and the mount is very compact. 
The corrections are excellent, and we can strongly rec- 
ommend this condenser for almost all kinds of work and 
for photography in particular. 
CHARLES BAKER’S DEMONSTRATIONS OF MICROSCOPIC 
MANIPULATIONS.—This new departure fully justifies it- 
self and the attendance has steadily increased. Eleven 
demonstrations have been given up to the time of writing, 
and the total attendance has been 124, giving an average 
of eleven. Three persons attended the first demonstra- 
tion, whilst eighteen attended the last —an increase which 
testifies to their value.—Science Gossip. 
EDITORIAL. 
KEY To THE INFUSORIA.—We have received copy for 
a Key to the Infusoria which will cover about 25 pages — 
of the Journal and be issued in our May number. Hight 
pages already in type, are held over in order that the 
Key may be published all together. This explains the 
Journal being a little smaller than usual this month. 
Tat Drop.—‘When, with your imperfect microscope 
you examine, for instance a drop of water, or simply air, 
what do you see? You notice millions of infusoria,—mil- 
lions of atoms, do you not? Do you know what air and a 
drop of water are?” Thus writes Agnes KE. Marsland in 
“Light on Occult Science,” p, 22. She labels herself: 
‘‘Graduate of the Univerity of Cambridge, England,” but 
we do not believe that any Cambridge graduate could be 
so ignorant regarding infusoria. 
DIAMETERS.—A new subscriber asks what part of an 
