COINAGES OF THE BRAIN. 295 



of centres and chief departments, there exist in the body numerous 

 other foci, so to speak, whence impressions may be reflected and 

 rearranged. Next in importance to the brain, we find the spinal cord 

 to act as a nerve-centre ; and it is perhaps the only focus of nerve 

 power, in addition to the brain, of which special mention need be 

 made at present. One observes how the cord may serve as a centre 

 in those too frequent cases of shock to the spine seen after railway 

 accidents and similar exigencies of life. The patient with a severely 

 injured cord is practically dead to sensation below the seat of injury, 

 is powerless to move his legs, and yet will have his limbs thrown into 

 violent convulsions when the soles of his feet are tickled. Over 

 this latter action he has no control, just as he has no knowledge of 

 the irritating cause beyond what his eyes reveal. Yet the explanation 

 is clear. The sensory impulse given to the soles of the feet passes 

 up the spinal cord to the nearest centre in the cord below the seat of 

 injury, and is therefrom reflected to the muscles of the legs, producing 

 the contortions in question. And more wonderful still is the case 

 of that physiologically useful animal the frog, which, lacking its head, 

 behaves itself as does a whole and sound amphibian ; wipes off with 

 one foot a drop of vinegar which has been placed on the other ; 

 manoeuvres its legs when in a difficulty regarding the removal of the 

 vinegar ; keeps its balance on your shifting hand ; preserves its 

 equilibrium with the agility of an acrobat ; and otherwise comports 

 itself in a fashion which strikes awe to the uninitiated mind, but which 

 demonstrates clearly enough the functions of the spinal cord as a 

 nerve-centre to the physiological understanding. 



From the study of the mechanism of sensations in general we may 

 profitably turn to that of sensations in particular, wherein we shall 

 find our elementary knowledge not 'merely an aid, but an absolute 

 essential, towards a clear appreciation of the unusual and strange as 

 well as of the familiar in human existence. The thoughts and con- 

 cepts we entertain of the world around us may be regarded as the 

 impressions, more or less thoroughly fixed, of sensations which have 

 been conveyed to us by many and varied channels from that outer 

 universe. How the impressions became fixed, or how we are enabled 

 to reproduce them almost at will from the memory-chambers of the 

 brain, are subjects which may perchance be briefly glanced at later 

 on. Suffice it to remark that knowledge largely, if not completely, 

 consists in a physiological sense of " registered impressions," which 

 have become, in some mysterious fashion, part and parcel of the 

 cerebral substance, and which have been stamped more or less 

 indelibly on the organ of mind. " The coinage of the brain," in 

 very truth, derives its rough form and shape from the outer 

 universe ; it is the brain itself which thereafter stamps and issues 

 the refined products as the thoughts of men. These thoughts thus 



