On the electrical phenomena accompanying secretion in the skin of the frog / by W.M. Bayliss and J. Rose Bradford.

  • Bayliss, William Maddock, Sir, 1860-1924.
Date:
[1885?]
Catalogue details

Licence: Public Domain Mark

Credit: On the electrical phenomena accompanying secretion in the skin of the frog / by W.M. Bayliss and J. Rose Bradford. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    effect of tap-water dropped on the preparation but could detect no diminution whatever in the excitatory effect. As regards the Current of Rest in other Amphibia, one observation was made upon the green tree frog (Hyla arborea), and here the E.M.F. of the skin of back was found to be 11931 f.v. The E.M.F. obtained by leading off the lateral glands of the Salamander on one side and the hind leg (which had beeu amputated and replaced in its position) on the opposite side, was always very great, though of course how much of it was due to the glands it is impossible to say; it amounted to from 20000 f.v. to 30000 f.v. As will be seen below the excitatory variation in this creature is also very large. Electrical Excitatory Change. We have already had occasion to remark that Engelmann asserts that the electrical change occurring in the glands of the frog’s skin, on excitation of the nerves supplying it, is of the nature of a negative variation of the current of rest; i.e. the mouths of the glands become less negative to the bases. Hermann on the contrary sees a positive variation either alone or accompanied by a small preceding negative variation, i.e. the so-called negative “Vorschlag.” He admits however that he has very occasionally seen a pure negative variation. These contradictory results puzzled us at first, since it was difficult to under- stand how two such skilled investigators could have arrived at directly opposite results in so simple a matter ; but in the course of our experi- ments we succeeded in clearing up the discrepancy, as will be after- wards seen. In almost all our experiments the English frog, (Rana temporaria) was used, prepared however in two different ways, both due to Her- mann. Hermann, however, used the German frog, i.e. Rana esculenta. The first preparation consisted of the skin of the back prepared in the following manner. The frog is decapitated, and the spinal cord de- stroyed. Two parallel incisions are made with scissors just on the dorsal side of the lateral swellings, and a transverse cut joins these two at the posterior extremity. This flap of skin remains in connection with the vertebral column only by the posterior primary branches of the spinal nerves. The vertebral column is now removed from the rest of the body by similar incisions and then removed with the skin and attached nerves to the moist chamber, care being taken not to stretch or otherwise injure the nerves.