534 THE POPULAR SCIENCE MONTHLY. 



others, besides the permanent muscular contraction,, produce a pain 

 lasting as long as the nerve retains its excitability. The spinal mar- 

 row is one of the most active parts of the system. In the form of a 

 thick, whitish cord, lodged inside the vertebral column, it constitutes a 

 real prolongation of the brain, of which, under some circumstances, it 

 takes the place. The unconscious depositary of a part of the force 

 animating the limbs, by means of the nerves sent out from it, it trans- 

 mits to them their direction and power to move, while the brain is un- 

 aware of its action. This takes place in what are called reflex mo- 

 tions, and these occur in beheaded animals, through the simple excite- 

 ment, direct or indirect, of the spinal marrow. Experiments may be 

 cited, showing the action of electricity on those phenomena which 

 have their seat in the spinal marrow. If a frog is plunged into luke- 

 warm water, at a temperature of 40, it loses respiration, feeling, 

 and motion, and would die if kept in it a long time. "When taken out 

 of the water, and placed in this state under the action of the current, 

 it contracts strongly when its vertebral column is electrified by an as- 

 cending charge ; but no motion follows if the descending current is 

 applied. On the other hand, if the latter is sent into a beheaded ani- 

 mal, stimulated to reflex motions, by the excitement of the spine, it 

 tends, as experiment shows, to paralyze these motions. In general, 

 this is the law discovered by Onimus and Legros the ascending bat- 

 tery-current, directed on the spine, increases the excitability of that 

 organ, and consequently its power of producing reflex phenomena; 

 the descending current, on the contrary, acts in the reverse way. 



When the brain of animals is directly electrified, the modifications 

 in circulation already spoken of result, but no special phenomena are 

 observed. The animal shows no pain, and makes no movement, ex- 

 periencing a tendency toward sleep, a sort of calm and stupor. Some 

 physicians have gone so far as to propose electrization of the brain as 

 a means of developing and perfecting the mental powers. Nothing 

 hitherto justifies the belief that such a course could have the slightest 

 influence for good over the functions of thought. On the contrary, it 

 is verv certain that the electric agent must be applied only with ex- 

 treme caution to the regions of the head, and that it very easily occa- 

 sions mischief in them. A strong current might readily cause rupture 

 of the vessels, and dangerous haemorrhage in consequence. 



Ao-ain, electricity stimulates all the organs of sense. Directed 

 upon the retina, it excites it, producing sensations of glare and daz- 

 zling. When sent through the organ of hearing, it produces there a 

 peculiar buzzing noise, and, if brought in contact with the tongue, it 

 calls forth a very characteristic metallic and styptic sensation. And 

 in the olfactory mucous membrane it creates a sneezing irritation, and 

 also, it seems, an odor of ammonia. 



The currents not only act on the cerebro-spinal nerves, and the 

 muscles concerned in life, as related outwardly, but affect also the parts 



