YAWNING AND SNEEZING 459 



The act of stretching may be called the completion 

 of the act of yawning above described. It is equally, 

 or even more generally, apparent throughout the upper 

 regions of animal life, and is indulged in with an inspiring 

 air of satisfaction and energy, which, in many instances, 

 is followed by an evident improvement in morale and 

 physique alike of its subject. 



A deeper inspiration and a consequently full thorax 

 are again, as in the yawn, the starting-points of the 

 series of movements which constitute " the stretch. " 

 With the deep inspiration the arm, or arms, are raised 

 to various heights and angles, turned and twisted, the 

 neck, with the head, is pulled backwards until its 

 anterior muscles are put well on the stretch, when an 

 undulatory movement of the muscles of the trunk, 

 from top to bottom, sends a wave of curvature down 

 the spinal column, which loses itself in the lower limbs, 

 and is projected, alternately flexing and extending them, 

 to their farthest extremities these movements sometimes 

 repeating themselves again and again. 



On a patient analysis of the phenomena, constituting 

 an " act of stretching," it is seen that the first " motor 

 impulse," after the initial deep inspiration, is communi- 

 cated to the " extensor musculature," which responds by 

 inducing an almost simultaneous or immediately consecutive 

 .contraction^ by which the dorsal aspect of the body is 

 shortened and the posterior surfaces of the limbs 

 tightened, throwing the weight of -the body, if recum- 

 bent, on to the occiput and heels. This contraction, 

 after continuing one or more seconds, relaxes, and is 

 succeeded by a second " motor impulse," which is com- 

 municated to the " flexor musculature," and the ventral 

 aspect of the body and limbs, whereby the body and 

 limbs are made to form an arc of a circle by bending 

 forward the head and thorax and tilting upwards the 

 feet and toes. 



These impulses, and consequent muscular contractions, 

 when well marked, are sufficient to bend the body in 

 either or both directions, and even laterally, by a slight 

 alteration and addition to muscular action, to an angle 

 of from ten to fifteen degrees, and are continued in 



