THe MIcRoscoPe. Bg) 
crushing the large females with a compressorium I have in 
many cases liberated the young and have seen them swim away 
as though it were a natural birth. 
—___—< ¢ >__—_ 
THE FACILITY NOSE-PIECE. 
JAS, L. PEASE. 
HIS Nose-piece, as usually made, attaches to the stand by the 
shank which has the “society screw” and is designed as a 
permanent attachment. When in position it occupies less than 
half an inch of the working distance. 
The rings are made to screw on the shanks of the objec- 
tives and may remain permanently attached for they do not 
interfere with closing the boxes in the usual manner. 
There are three steel jaws within the nose-piece that are 
operated upon by the milled ring that appears on the outer 
surface. A partial revolution of the milled ring causes the jaws 
to project inward and engage in the groove on the outer sur- 
face of the objective ring and thus the objective is held securely 
and firmly in position. 
With this devise the changing of objectives is accomplished 
very quickly. The outer surface of the objective ring being 
perfectly round, (7. e. without projecting lugs to enter corres- 
ponding depressions in the nose-piece) the objective is not only 
readily placed in position but an adjustable objective may be 
placed in the position desired for the best exposure of its mark- 
ings. 
The “grip” of the jaws is sufficient to prevent any adjust- 
able objective from turning in the nose-piece when the collar 
adjustment is operated. 
(The above was written at the request of the editor, in response to 
the expressed wishes of a number of subscribers.) 
—_4.6 >—___—__ 
STUDIES IN HISTOLOGY. 
Cc. H. STOWELL. 
LESSON V. 
METALLIC STAINS. 
NITRATE OF SILVER. 
ee. of silver has the property of acting upon the 
cement substance between the epithelial and endothelial 
cells, and thus their outlines are accurately mapped out. It 
