STRIATED MUSCLE. 



69 



ing to the condition of the muscle. We shall consider 

 this explanation again when analyzing the ultimate action 

 that constitutes what is called the contraction of the 

 muscle. 



The principal feature in the study of the muscle is that it 

 changes its shape, and appears under two different forms; 

 thus a fusiform muscle, meeting with no opposition, becomes 

 globular under certain circumstances. The former condition 

 is usually called the state of repose, and the latter the state 

 of action. In order not to anticipate, we will call the first 

 simply form No. 1 ; the second, form No. 2 (Fig. 18). 



Fig. 18. The muscle, under forms No. 1 and No. 2.* 



We will, then, proceed to examine the properties and phe- 

 nomena exhibited by the muscle under form No. 1; and, 

 afterwards, those under form No. 2. As the muscle origi- 

 nates from the globules, and still represents, in its structure, 

 the elements of which they are chiefly composed, we shall find 

 both in it, and in the two forms which it takes, the principal 

 physiological properties of the globule ; viz., elasticity, chem- 

 ical phenomena, electro-motor power, etc. 



These properties being known, we shall speak more at 

 large of those which are chiefly made use of in the animal 



* SH, Articulation of the shoulder joint. CH, Articulation of the elbow. 

 H, Humerus. B, Biceps in the state of repose (form No. 1). B', Biceps assum- 

 ing the form No. 2, in consequence of section of its tendon. (The tendon of 

 the biceps is actually inserted into the radius, but since, during flexion, the lat- 

 ter becomes a fixed body with the ulna, the fore-arm is represented in the dia- 

 gram by a latter bone, in which the biceps appears to be inserted.) 



