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

of urine is suspended, and at the same time there is an excessive flow of saliva. It is, therefore, fairly concluded, that the vagi do not form the motory system of the heart, but that they rather regu- late the rhythmatic heart actions, which themselves are caused only by the sympathetic fibres. The aorta, large arteries and veins, and the smaller blood vessels are very differently affected by the electric current, and that in proportion to their structure and their attending nerves. Probably the aorta in man does not contract under its influence; but this is accounted for, when we recollect that the aorta is mostly made up of clastic fibres, while there are very few contractile fibre-cells. These latter are supposed to be so few, and so deficient in power, even when excited by elec- tricity, that they are not able to overcome the elastic forces which constantly tend to retain the aorta open. This is true of man, but not so as regards the aorta of the horse, ox, or sheep; for here we find the aorta contains a very much larger proportion of the contractile fibre-cells than is found in the aorta of man. But in the human organism we find, again, that in the smaller blood vessels, and particularly in the smaller arteries, the con- tractile fibre-cells largely predominate in their structure; and this accounts for their strong contractions under the influence of the electric current. True to the nature of their contractile fibre-cells, they are moderate in beginning to contract, and that only after the action of the current for some appreciable time; and even sometimes after the electrodes are taken away are they seen to continue to increase their contractions to their maximum, and then as deliberately take on their normal state; which is so un- like the phenomena of electi'o-muscular contraction, on the one hand, and yet, on the other, as unlike the negative action of tissues that are composed simply of elastic fibres. The action of electricity on the blood is mainly chemical; and therefore we might expect that Galvanic currents would have more effect than Faradaic, or than frictional electricity ; and so it is. If we use galvanic electricity, we are able to coagidate fresh blood, taken either from an artery, vein, or capillary; and this can be done, moreover, where the blood is flowing in the vessels of the living body. If we act upon arterial blood by a