A text-book of human physiology / by Dr. Robert Tigerstedt ... tr. from the 3d German ed. and edited by John R. Murlin ... with an introduction to the English ed., by Professor Graham Lusk.

  • Robert Tigerstedt
Date:
1906
Catalogue details

Licence: Public Domain Mark

Credit: A text-book of human physiology / by Dr. Robert Tigerstedt ... tr. from the 3d German ed. and edited by John R. Murlin ... with an introduction to the English ed., by Professor Graham Lusk. 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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    nV We find similar skin currents in all ^lammalia including man. If the two hands or the two feet of a man be led off symmetrically to the gal- vanometer and one arm or one foot be moved voluntarily the needle makes an excursion, which is not caused by the muscular contraction in itself but by the process of secretion going on at the same time in the sweat glands of the contracted extremity. This current passes from the outside to the inside of the skin. A very similar skin current has been observed in the sweating of different mammals. Biedermann observes that one cannot draw a sharp line of separation between current of rest and current of action in epithelial and glandular cells, for -the reason that the differences of tension met with e are always the expression of differences in the chemical relations of the neighboring parts. From this point of view it appears quite arbitrary, or incorrect indeed, to speak of the current of rest in contradistinction to the current of action of a glandular structure, since in both cases one deals with the effects of certain metabf)lic processes going on in detinite parts of the cell body, which by direct or indirect stimulation are only changed in one direction or another. It is better, there- fore, to say that'the ordinary skin current is pro- duced by the negativity of that portion of the cell which is being transformed into mucus, toward the protoplasmic portion (Hermann). As above remarked, this inwardly directed current may, under certain circumstances, un- dergo a complete reversal. To explain this we can make only one assumption, namely, that the same epithelial cell has the power to act electi'i- cally sometimes in one sense, sometimes in the other. This is borne out by the fact that each cell is the seat of two different chemical processes (assimilation and dissimilation), which, going on at the same time, give rise to opposite tensions. The deviation occasionally observed would, ac- cording to this, always be the resultant of the two antagonistic forces (Hering, Biedermann). It is possible that a relationship similar to this exists between the chemical processes underlying' the secretion of water on the one hand and the seci'etion of organically specific constituents on the other (Biedermann). Perhaps from this point of view are to be explained certain results obtained with the digestive glands, of which more in Chapter VTT. Electrical currents have been demonstrated even in plants, where, just as in the animal tissues, an injured ])lace is found to be electro-negative to an uninjured place. Electrical effects appear 'also under a|)propriate circum- stances in certain parts of plants which are entirely uninjured. Thu<. differ- ences of tension are obtained between cells or cell territories of an organ or of a whole plant which maintain different chemical relations to each other. For example, according to Waller, the processes taking place in the forma- FlG 30.—The cramp fish, Torpedo, dissected to sliow electric ap- paratus, after Huxley; b, gills; c, brain; c, electric organ; y, cranium; ine, spinal cord; np, branches of pneumogastric nerves to electric organs; o, eye.
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