381 
Dissection and Injection of Living Cells. 
prevent a coverslip from sliding beyond it. The trough of the 
chamber should be from f in. to J in. wide. The strips are cemented 
with any ordinary glass cement. Heated Canada balsam serves 
well. Near the closed end of the trough a small strip of glass 
should be cemented across the trough to provide a well for water. 
When cementing the long strips to the base care must be taken 
to have the top surface of the strips horizontal. This may be done, 
while the cement is still soft, by focusing on the upper surface of 
the strips and by manipulating the strips until all parts of the 
surface lie in one focal plane. 
The well in the chamber is to be filled with water, and, in 
order to distribute the moisture throughout the chamber, strips of 
Fig. 4. — Moist chamber and cardboard trough for closing open 
end of chamber. When the needles are in place (o*f fig. 3) the 
trough is placed over shanks of needles (dotted line s at open end of 
chamber) and filled with vaseline. 
blotting paper should be placed along the sides of the trough with 
the inner end in the water well. Instead of the well one may use 
cross strips of blotting paper. This moist chamber is designed 
for coverslips of a size 24 by 40 mm. The coverslip is sealed on 
the chamber with vaseline. Square coverslips may also be used 
provided the rest of the chamber be roofed with other strips of 
cover glass. 
The hanging drop containing the cells or tissue to be operated 
upon is placed on the coverslip, which is then inverted over the 
moist chamber. To prevent the vaseline from spreading on the 
cover glass and from contaminating the hanging drop, a thin film 
of melted paraffin may be spread and cooled on the cover glass 
bounding the area to be occupied by the hanging drop. 
