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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    patients cannot take food, in those recovering from con- suming febrile diseases, in pseudo-leukasmia, and in hydremia; but in leukaemia there is also an absolute and relative in- crease in the number of the white corpuscles, and in certain forms of anaemia and cachexia—e.g. in absolute starvation and advanced tuberculosis and cancer—in addition to a deficiency of haemoglobin, there is also a diminution in the total quan- tity of blood. Not only is there here a change of colour of the blood, but there is an adaptation of the vessels of the skin to the diminished supply, i. e. the stream-bed of the skin becomes contracted in simple diminution of the blood. This is seen, too, after loss of blood from wounds and opera- tions, and in cases of intestinal parasites, as in pernicious anaemia. After severe haemorrhage in young persons, the skin becomes waxy, yellow, and transparent, from the regu- lative contraction of all the vessels of the skin and absorption of tissue-fluids by the veins and lymphatics. The ashy-grey colour of the skin in cholera is similarly due to a general contraction of the cutaneous vessels, com- bined with increasing cyanosis of the blood, as the velocity of its current diminishes. The fall of temperature and in- crease of the vascular tone of the skin resulting from these quantitative anomalies of the blood, approximate such cases to the isolated anaemia, which we shall now consider, and in which qualitative changes are of course excluded. This anaemia may involve the whole skin or only parts of it. When the whole skin is anaemic, either the circulation in general or the central nervous system must be affected. Contraction of the cutaneous arteries always runs parallel with the anaemia, and sometimes this contraction follows a diminished blood supply ; but whether the arterial constric- tion or the diminution of blood in the skin be primary in any given case, is often as difficult to determine as in phy- siological experiments. Arterial constriction is certainly primary in the death agony, and it causes that unfortunate pallor which makes the post-mortem study of most dermatoses so difficult, and that of the circulation anomalies impossible. The paleness accompanying cardiac weakness, especially that which precedes fainting and obviates a dangerous fall of blood-pressure, is also probably primary in nature. To the