the direction of the current, because the conductivity of a current, flowing long in the same direction, decreases, while with a change in the direction it increases.

9. The extrapolar descending anelectrotonus is above all to be used when we wish to bring back to the normal condition a pathologically increased excitability, or abnormal irritation at the periphery of a nerve. The intensity of the desired effect is as the strength of the current, the length of the time of closure of the circuit, the greatness of the interpolar tract, and, finally, the shortness of the distance between the anode and the affected organ.

10. The extrapolar descending catelectrotonus is, on the contrary, to be used where we wish again to excite the sunken excitability or lessened sensation at the periphery of the nerve of the respective muscle.

11. From the same points of view the indications for the local production of extrapolar ascending anelectrotonus and catelectrotonus are to be sketched out, and consequently there come into consideration the extrapolar ascending anelectrotonus with increased, and the ascending catelectrotonus with decreased irritability, as applicable respectively to the cerebro-spinal shoots and the central sources of the nerve fibres.

12. There is no doubt that we can, by means of a constant current, even of tolerable strength, affect through their bony coverings the brain and spinal marrow.

FIFTH SECTION.

ON THE VARIOUS KINDS OF APPARATUS CONSTRUCTED ESPE CIALLY FOR THERAPEUTICAL PURPOSES.

I. GALVANIC APPARATUS.

AMONG the many apparatuses which have been constructed for the purpose of exciting galvanic electricity for special therapeutic uses, and which have been described and praised according to their different forms, as chain, curved, and binding apparatus, we find some which have no appreciable physical effect-as the Goldberger chain; others whose working is rendered much simpler by means of movable zinc and copper plates combined with one another, which may be laid on any portion of the body-as Romershausen's galvano-electrical curve, Récamier's cataplasme galvanique, Kunzeman's apparatus, etc. All these we will pass by in silence, and notice only Pulvermacher's chain, which produces a much more marked physical and chemical effect. This consists of a smaller or greater number of movable members combined with one another, each one of which consists of a small wooden cylinder, around which there are laid, yet without touching each other, a zinc wire and a gilded copper wire having a spiral form. The individual members are connected with one another by means of small metallic rings which take up the zinc wire of one member and the copper wire of the next following. Each time before using it, the series is placed in vinegar, by means of which a tolerably strong electrical

ders d, which have a circumference of 13", so that each of them presents 78", and all four, 312". Within these there stand, on pedestals of stone, the clay cells e, 44" high and 31" in diameter, into which the platinum stars f dip, which are furnished with glass covers, and have attached to their upper portion (as the zinc) a small copper piece for connecting with the conducting wires. Each platinum star consists of three plates, 3" 10" high, 2" 9"" broad, united by means of a platinum clamp, and bent in such a way as to form a six-rayed star, having a working surface of about 250 ".

At the crossing of the partitions of the chest is placed the commutator A. This consists of a wooden column having on its upper slightly concave end eight little cups, 4"" broad, namely PPPP in an inner circle, and ZZZZ in an outer for

current is produced, lasting for about half an hour. To increase the quantity of the electrical current, a series composed of larger members must be used; but, to increase the intensity, the number of members must be increased. This apparatus deflects quite perceptibly the galvanometer needle, decomposes water, and causes reddening, swelling, and blistering of the skin, and, in short, brings about chemical and physical acts.'

[In the NEW YORK MEDICAL JOURNAL for November, 1865, I described a form of galvanic battery similar, in general features, to those referred to in the text, but possessed of many advantages. I referred to it in connec