HEATING AND COOLING. 



221 



Effect of heating- and cooling on the character of the 12 

 muscular contraction. 



Required: Frog-heart support on the general stand, heating cylinder 

 with funnel, and two pieces of rubber tubing 25 cm long, vulcanite lid 

 for the well of the cylinder; this has a radial cut in it, so that 

 it can be applied after the muscle is fixed in position. Thermometer, 

 tin can with spout for pouring water into the funnel, tin mug to receive 

 the outflow from the cylinder. Inductorium, 2 keys, 2 Leclanche 

 cells, 7 wires, 10 cm fine copper wire for attaching the femur. Drum 

 contact in P circuit, and speed to draw the curve out to 3 cm , S wires 

 attached as in the figure. Gastrocnemius with a third of the femur 

 attached. 



FIG. 41. W Water jacket (cylinder) upon G, the frog-heart support. F Funnel 

 for inflow attached to the side bar of the general stand. T Thermometer. U Bent 

 bar for attachment of muscle, detachable by a side twist. 



The femur is connected to one side of the inverted recorder R by a fine copper 

 wire, the writing point is at the other end. In the well above G is a glass cylinder 

 for immersing the muscle in fluid. S Connections of S circuit for stimulating. 



Remove U, place the cylinder in position on the frog-heart 

 support (as shown in Fig. 41), with a little normal saline in 

 the glass, to keep the muscle from drying. 



