Eight lectures on the signs of life from their electrical aspect / by Augustus D. Waller.

  • Augustus Desiré Waller
Date:
1903
Catalogue details

Licence: Public Domain Mark

Credit: Eight lectures on the signs of life from their electrical aspect / by Augustus D. Waller. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    ever omitted to control the result observed on the living thing by the identical test applied to the same thing killed. § ']']. Fallacies. — Fallacy of the electrodes arises from polarisation; our unpolarisable electrodes are not abso- lutely unpolarisable, and may accidentally be quite sensibly polarisable. Their polarisation currents, anomalous or positive, as well as normal or negative, are most manifest with a constant current, much less so, but still sensibly so, with induced currents. We have made use of induced currents only, and shall therefore restrict our attention to these. With single shocks I do not think there is any liability to fallacy; an unequivocal or homodrome blaze-current cannot be simulated by anomalous polarisation, which is a rare and feeble effect manifested by a defective electrode, and quite absent from a properly prepared electrode. An equivocal or anti- drome blaze-current might at first sight be taken as being due to ordinary polarisation, since it is of the same direction ; but the magnitude of the response, its absence from the electrodes themselves when joined, and from the tissue itself when killed, will leave us in no doubt as to the physiological character of the reaction. It is only in the cases where single shocks having proved to be ineffective, we have recourse to the further test of tetanisation by alternating currents, in order to bring out a summated effect (p. 68), that there is any real possibility of deception. Distinguish between the two cases: (i) that in which the alternating currents are passed through the galvano- meter and test-object; (2) that in which they are passed through the test object only while the galvanometer is short-circuited. The first of these two dispositions reproduces an arrangement that was first adopted by V. Fleischl in the case of nerve, and that I have already considered at some length in that connec- tion. The opposed make-and-break currents are supposed to neutralise each other through the galvanometer, and such deflec- tion as occurs is attributed to an electro-motive action of the test-object. This deflection occurs in the direction of the break current, i.e.^ is such as would be produced by a physiological reaction in that direction, or as a physical reaction—the sum
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