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

this difference occurs in the living muscles of man, and that hy the augmentation of chemical changes, the heat of the part is sensibly increased. More blood is attracted to the capillary ves- sels, particularly those of the muscular substance whereby the bulk of the muscles is expanded and actually increased. The very fact that there is more blood attracted to these tissues pro- duces, under this more lively induced action, an increased nutrition. The human brain, we know, is composed of gray and white matter, in dis- tinct layers, yet folded up in a wondrously compact manner, like a very economical voltaic battery. If the brain were unfolded and spread out, it would be seen to have the layer of gray substance placed first over its surface, while the white is inside, and this latter showing numerous glistening fibres, or conductors, converging towards a centre. In the composition of the brain, we know there is a large amount of phosphorus, combined with a profusion of arterial blood and oily matter; and is capable of a peculiar excitation, somewhat analogous to galvanic electricity. From analogy, says Dr. O'Reilly, of New York, it would appear, in fact, that the arrangement of voltaic or gal- vanic pairs, in a battery for yielding large quantities of electricity, was founded on the very same principles that here exist; and this appears to be borne out to a certain extent by facts. When a man long overworks his brain, phos- phorus is found in the urine, while the nervous energy and endurance are diminished. A tranquil sleep or a longer rest is required to allow the process of recuperation, and the aid of electricity helps the repairing process. It is a further remarkable fact that whereas the gray substance is placed on the external surface of the convolutions of the brain, in the spinal marrow it is located internally. Equally worthy of notice is it, that the current of the immaterial agent in the brain is from the surface towards the centre and base, whilst in the spinal cord, mark, it is from within to the surface. In both cases, however, the arrangement is in accordance with the origin of the roots of the nerves, as they are found situated in the brain and in the spinal cord. The conclusion, from these premises, says the doctor, would be evidence that the phosphorus acts on the gray substance, so as to produce the immaterial cur- rent or nerve agent, in a similar way as the oxygen unites with the tissues and the minute and pervading organic nerves, in the maintenance of heat, and that immaterial agent termed life. In fact we know that " animal electricity " and " nerve force," though not precisely identical, are most intricately connected. We know that by electric excitation we can produce an increase of bulk and heat in the living tissues, or a return of these where deficient. A strong direct primary current, occasionally quickly reversed, through contiguous electrodes, is the best for this end; it can also be accomplished by secondary currents. Giddiness is usually caused by a deficient supply of blood to