LESSON IX. 

 PROPERTIES OF CONTRACTILE TISSUE. 



1. Constant Current. 



Destroy the brain and spinal cord of a frog and 

 make a longitudinal incision through the skin of 

 the back of the thigh. With fine-pointed scissors 

 cut through the connective tissue between the 

 large semi-membranosus muscle and the small 

 biceps : the former lies on the inside of the thigh, 

 the latter is seen along the outer and lower 

 border of the semi-membranosus. The sciatic 

 nerve and the femoral artery will come into view; 

 at about the upper third of the thigh, the artery 

 will be seen to give off two small transverse 

 branches running, in the position of the frog, over 

 the nerve; from this point down to the knee, 

 isolate the nerve by tearing away with a "seeker" 

 the connective tissue around it ; if the tissue is 

 resistant it is ^better to lift up the nerve with a 

 seeker and to cut through the connective tissue 

 with fine scissors. Be careful not to, pinch the 

 nerve with the forceps, nor to put more strain 

 upon it than is absolutely necessary, and further 

 not to puncture the artery. 



