CHAPTER XIV 



Involuntary Muscle 



Stomach or bladder of frog. Take 



FIG. 56. Diagram of apparatus for re- 

 cording the contractions of a strip of 

 plain muscle immersed in Ringer's 

 solution, and for investigating the 

 action of drugs and animal extracts 

 upon the tissue. 



66 



either a transverse strip from the 

 stomach the frog should have 

 been recently fed or the whole 

 urinary bladder, fastening a 

 thread to each end. For re- 

 cording the contractions, which 

 may be spontaneous and rhyth- 

 mic, or may need to be elicited 

 by excitation, the apparatus 

 shown in Fig. 39 may be em- 

 ployed, the source of heat being 

 omitted. A better method is 

 that exhibited by Fig. 56, a glass 

 tube of the size and construction 

 shown in the diagram being 

 used. One end of the prepara- 

 tion is tied securely to a hooked 

 wire passing through a cork, 

 which closes the lower end of 

 the tube, and serving as an 

 electrode, whilst the other end 

 is attached by a cotton thread, 

 passing through the open upper 

 end of the tube, to the short 

 arm of a very light lever. The 

 tube has three lateral openings ; 

 one, near the bottom for inflow 

 of fluid, a second near the top 

 for outflow, and a third, closed 

 by a cork, through which a wire 

 is passed to serve as a second 

 electrode. The glass tube is 

 filled with Ringer's solution. 

 Bring fine wires from a battery 



