Selected monographs on dermatology / P.G. Unna [and others].

Date:
1893
Catalogue details

Licence: Public Domain Mark

Credit: Selected monographs on dermatology / P.G. Unna [and others]. Source: Wellcome Collection.

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    introduce unnecessary complications ; for peripheral ganglia, with the definite function of inhibition, we must assume to exist in the skin in any case. It is a well-known fact, noticed by all experimenters alike, that after section of all nerve tracks connecting the vessels with the central organ, the vessels gradually contract again, and acquire new tone, which, how- ever, never regains the old delicacy in reacting to external stimuli or the former resistance. The contraction can be explained by introducing between the passive stretching of the muscle tissue by the blood-pressure and the contraction of the muscle, a sensory element, sm, which, stimulated by the stretching of the muscle, leads the latter to contract (by the path sm—a). An independent tone, admitting of regu- lation within narrow limits, can, however, be established only by peripheral ganglia. According to our diagram, g remains intact, exercising an independent influence by the path g a, and counteracting the stretching of the vascular tube by the blood-pressure. The further reaction of the centrally paralysed cutaneous vessels, compared with that of unparalysed vessels, shows us how to decide with certainty by what paths the remaining active stimuli must travel. Ostroumoff found that nicotine poisoning, or poisoning by C02 (by suspending artificial respiration), only produced cutaneous hypersemia when the nerves of the vessels were untouched. These stimuli hence travel by the path se—m —g, if we assume that the poisoning starts from the blood itself ; or by the path m—g, if it affects the vaso-motor centre directly. Only very severe nicotine poisoning also dilated the vessels paralysed from their centre. Must we therefore also assume a direct path se—g ? Probably not, for this paralysis may be looked upon as a direct action of the poison on the terminal of the tract g—a, independently governed by the vascular ganglion. Latschenberger and Deahna1 found, moreover, that cen- tripetal fibres run from all vessels, and that their stimulation causes dilatation in the vascular area of the artery, and tends to lower the pressure which has been raised by arterial con- striction in a self-regulative manner. These impulses travel by the path se—m—g. Starting with the proof of such