OF DENISON UNIVERSITY. 
13 
tine, (or other coloring injections). All the rubber tubes are provided 
with thumb pinchers. The advantage of the three pressure tubes is 
obvious, as the normal solution may be used and then by closing the 
pincher leading to the pressure flask the pressure is all ready for the 
colored injections and, in case both colors are to be used at once, both 
injecting fluids will be under the same pressure. 
Our injection bottles C, are made of clamp top cans, by drilling 
two holes through the top to one side of the clamp, a little larger than 
the glass tube to be used, thus allowing a rubber collar to be used 
around the glass tube and furnishing a movable and air tight union. 
The long tube which reaches to the bottom of the bottle is the one to 
which the canula tube is attached. If all unions are tight the flow of 
the liquid from the upper to the lower flask should force an equal bulk 
of injecting fluid from the injection bottles, less the amount of fluid re- 
vuired to produce the first pressure, with a single charging of the ap- 
paratus. 
A saturated salt solution is found to work admirably as a pressure 
liquid. The pressure is regulated by shifting the friction bracket and 
the pressure is read from the mercury scale. 
