96 



The experiment on the sartorius muscle confirms the fact, 

 as shown by histological examination, that no nerve fibers are 

 present in the ends of tbe muscle ; for the same experiment 

 shows the same results for two or three millimeters of the 

 distal end of the muscle. Muscle fiber is not excited by 

 glycerin and not until enough of the muscle was cut away, to 

 expose the nerve fibers in the muscle did the irregular twitch- 

 ings occur. 



XXV 



338. The Moist Chamber. Muscle and nerve tissue 

 dry shortly after their removal from the body and the use- 

 fulness of an experiment is, sometimes, much hampered by 

 this fact. In order to prevent drying, a moist chamber is 

 employed. This apparatus consists of a glass cover fitting 

 tightly over the myograph (muscle electrodes). A thread 

 passing through an aperture connects the muscle with the 

 recording lever. A few pieces of blotting paper wet with the 

 normal saline solution placed in the chamber keeps the air 

 moist. 



339. The Musci<e Curve. If a stimulus of very short 

 duration be applied to a muscle or its nerve, the mtiscle 

 responds by giving a contraction of very short duration. 

 This is termed a simple twitch. ."'.i 



The curve obtained from a muscle falls naturally into 

 three parts : 



(1). From the point of stimulation (a) to the point of 

 commencing contraction (b). This is known as the Latent 

 Period. During this time there is no change in the length of 

 the muscle. A muscle does not contract simultaneously all 

 over, 'but the contraction^starts at some one spot and then 

 spreads in a wave-like manner over the rest of the muscle. 

 Following an excitation at one spot, the fibers in that position 

 contract, but do not at first lead to a movement of the record- 

 ing lever but rather to a stretching of the remainder of the 

 fiber, both above and below the point of contracting. The 

 parts which have to be moved possess some inertia. 



(2). From the point of commencing contraction (b) to 

 the highest point of the curve (c). This is termed the Period 



