THE PHYSIOLOGY OF MUSCLE 



481 



FIG. 268 



and it has attached to it a long bone useful as a means of holding it 

 firmly in the apparatus. The advantages of frogs over other animals 

 for this purpose are numerous, but the selection is confined to poikilo- 

 therms (" cold-blooded" animals), because in them the muscles when 

 properly cared for will live days in 

 comparison with the hours which the 

 muscles of homotherms can be kept 

 alive with only much greater care. 



One thing it is pleasant to contin- 

 ually remember: that any consider- 

 able injury to the brain or even to the 

 spinal cord produces most certainly, 

 without any doubt whatever, com- 

 plete abolition of consciousness and 

 the pain-sense, leaving the animal a 

 mechanism only, composed of slowly 

 dying tissues of great scientific use- 

 fulness. 



Expt. 36. Varieties of Energy that 

 will Stimulate Muscle. (Apparatus: 

 Gastrocnemius muscle, glass plate, 

 glass rod, key, dry-cell, wires, satu- 

 rated solution sodium chloride, Bun- 

 sen burner, seeker, ice, small beaker.) 

 Muscle can be stimulated by four of 

 the eight known aspects of energy in 

 addition to the normal nervous force 

 of unknown nature. These four are : 

 (A) kinetic, (B) electric, (C) chemic, 

 and (D) thermic energy. 



A. Kinetic Stimulation. As the 

 muscle lies on the glass plate prod it 

 with the small sharp end of the glass 

 rod, or pinch it. It will contract. 



B. Electric. Hold the wires on the 

 muscle and close the key (the "make" 

 of the current). The muscle twitches. 

 Open the key ("break") and the 

 muscle contracts again (but not so 

 strongly). Static electricity will stim- 

 ulate as well as galvanic.. 



C. Chemic. Place a small drop of the saturated sodium chloride 

 solution on the muscle. It will soon contract. Wash the muscle. 

 Drying (loss of water from the protoplasm) stimulates the muscle, as 

 may be seen by allowing it to partially dry. Exosmosis of salines is a 

 stimulation: immerse the muscle in a beaker of distilled water. Con- 

 tractions soon appear 



31 



The frog's nervous system : Ol, olfactory 

 nerves; O, eye; Op, optic nerve; Vg, Gas- 

 serian ganglion ; Xg, vagal ganglion; 

 Spn 1, first spinal nerve; Br, brachial nerve; 

 Sg 1 to Sg 10, the ten ganglia of the 

 sympathetic; Js, ischial nerve. (Ecker.) 



