Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.

sation are capable of exciting the nerves of motion, which are in their neighborhood; and they may produce this effect, even, when the spinal cord has been severed from the brain; because their relation to the gray matter of the cord is such that their state of excitement, however varied, is readily extended to it. Neither is this hypothesis accepted in full, as such. There is still another and more recent hypothesis put forth by Drs. Todd and Bowman, of London, which assumes that all the spinal and encephalic nerves, of whatever function, are im- planted in the gray matter of the segments of the cerebrospinal centre, with which they are severally connected, and do not pass beyond. The several segments of the cerebrospinal axis arc connected with each other through the continuity of the gray matter from one to another, and through the medium of com- missural fibres, which pass between them. Motor or sensitive impulses, through these means, may be propagated from seg- ment rb segment; and a stimulus conveyed to any segment from the periphery may cither simultaneously affect the train, and cause a sensation, or it may be reflected upon the motor nerves of that particular segment, and stimulate their depending mus- cles to contract. Or, indeed, both these effects may take place at the same moment, as the result of one and the same stimulus. According to these gentlemen, each segment of the cord, so long as it retains its proper commissural connection with the brain, (by both commissural fibres and continuous gray matter,) is in fact, and effect, part and parcel of the centre of volition, as well as that of sensation ; and the mind is as directly associated with each segment of the cord as it is with any portion of the en- cephalon. Just let that commissural connection be dissolved or severed, and the mind will immediately lose its hold upon the cord and its dependencies. But the various segments of that or- gan may, nevertheless, be acted upon still by physical impulse!:, and may still continue to evolve the nervous force in connection with the natural changes which may take place within. An abstruse writer in the British and Foreign Medico-Chirur- gical Review, remarks that the recent discovery of Mr. Grain- ger, viz., that from each root of a spinal nerve some fibrils are