442 STUDIES IN GENERAL PHYSIOLOGY 
That we are, indeed, dealing with the effects of a con- 
stant current is shown by the fact, first of all, that the longer 
the circuit is closed, the longer does secretion last, the 
greater is the amount of the secretion, and the greater 
the region in which the secretion occurs; secondly, that the 
secretory phenomena are brought about when the intensity 
of the current is raised very slowly. The breaking of the 
current, on the other hand, has no effect. 
2. The next question that presented itself was whether 
we dealt in this case with the effects of the current upon the 
skin or the glands themselves, or whether we had to do with 
a stimulation of the central nervous system. We next in- 
vestigated the action of the current upon animals in which 
the spinal cord had been cut. When a current was passed 
longitudinally through such animals, they behaved as though 
they consisted of two fully independent pieces. If we call 
that portion of the animal lying anterior to the cut the 
anterior animal, and that lying behind it the posterior 
animal, then the end of both the anterior animal and the 
posterior animal which was directed toward the anode secreted 
during the passage of a current longitudinally through the 
animal. In Figs.128 and 129 S marks the position at which 
the spinal cord was severed. In a descending current not 
only the piece ab (Fig. 128) at the head end of the animal 
secretes mucus, as in the case of the normal animal, but 
also the anterior region cd of the posterior part of the 
animal, which under otherwise similar conditions never 
secretes in the uninjured animal. When the current passes 
in an ascending direction, secretion occurs not only at the 
tail (cd, Fig. 129), as in the uninjured animal, but secretion 
occurs also at the posterior end of the anterior part of the 
animal (ab, Fig. 129). The secretion in the latter case often 
limits itself to the hindmost edge of the immediate vicinity 
of the wound, and does not extend forward until the current 
has passed through the animal for some time. 
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