Page:Popular Science Monthly Volume 42.djvu/37

Rh 2). It is a matter of ancient observation that such an attitude as this is associated with weak circulation, and it is probably more than three thousand years ago that the injunction was given: "Strengthen ye the weak hands and confirm the feeble knees; say to them that are of a fearful heart, Be strong, fear not" (,

3, 4). When the heart is stimulated by joy or hope, the attitude again becomes erect, and the gait brisk and elastic. It is by no means easy to distinguish exactly between the part played in this change by the motor cells of the nerve-centers and by the circulatory apparatus, for the activity of the motor cells on which muscular action depends is itself influenced to an enormous extent by the circulation of blood through the nerve-centers. We find an example of this in the attitude unconsciously assumed by any one engaged in conversation or argument. So long as he takes only a listless interest in the subject under discussion he may lie back

in the chair with his legs crossed and his arms either hanging down or his hands laid loosely in his lap (Fig. 3). As his interest increases his attitude becomes more erect (Fig. 4), and he sits straight up, with his hands folded or laid upon his knees instead