OF DENISON UNIVERSITY. I^ 



tine, (or other coloring injections). All the ruhher 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 

 pmcher 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, l)y 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 e(iual 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 a|>- 

 paratus. 



A saturated salt solution is found to work admirably as a i>ressure 

 liquid. The pressure is regulated by shifting the friction bracket and 

 the pressure is read from the mercury scale. 



