318 PHYSIOLOGY AND HEALTH. 



in order that the head should still be over the base or point 

 of support, the upper curvature is balanced by an opposite 

 lower curvature. While the upper part of the spine is curved 

 to the left, the lower part, at the loins, is curved to the right, 

 and the whole column assumes somewhat the shape of the 

 letter S in its lateral direction. At the same time, the lowest 

 and the highest portions are nearly straight, and the head is 

 vertically above the base of the column. (Fig. LX.) 



731. The same effect follows from a position sometimes 

 assumed in reading. The table is higher than the suspended 

 elbow, and the reader does not sit directly facing it, but 

 rather obliquely, and, lolling sidewise, raises the elbow upon 

 the table, and rests the head upon the hand. This raises the 

 shoulder, bends the spine, and produces the same result that 

 comes from the unnatural posture in writing and drawing. 

 If these positions are frequently changed, if one shoulder is 

 raised as often as the other, and neither elevation is continued 

 for a long time, no curvature of the spine will follow. But 

 if either bent position be assumed frequently, and maintained 

 for a long time, the cartilages will lose their elasticity, and 

 become .compressed on one side and expanded on the other. 

 In the natural form, the shoulders are of the same size; they 

 both rest upon the back of the chest, and lie upon the ribs, 

 which are fixed upon the spine. If we examine any active 

 boy, or any playful, healthy girl, we shall see that the shoulders 

 are exactly alike ; they are of the same height, and have the 

 same shape. But, if we examine many girls who are pursu- 

 ing or have finished their education, we shall find that one 

 of the shoulders is grown out, and is higher, and projects 

 farther forward than the other. 



732. The habits of school children, and especially of girls, 

 of students, clerks, draughtsmen, and of some others, create 

 a fearful frequency of this spinal distortion. Dr. Warren 

 says, " In the course of my observation, I have been able to 

 satisfy myself that about half the young females, brought up 

 as they are at present, (1845,) undergo some veritable and 

 obvious change of structure ; and, of the remainder, a large 



