A practical treatise on diseases of the skin / by Louis A. Duhring.

  • Duhring, Louis A., 1845-1913.
Date:
1882
Catalogue details

Licence: Public Domain Mark

Credit: A practical treatise on diseases of the skin / by Louis A. Duhring. Source: Wellcome Collection.

    661/694 (page 659)
    may be briefly referred to. Considerable attention has been devoted to the minute anatomy of the head of the pediculus corporis by Landois* and Schiodte.f The latter of these investigators, whose studies are the more recent, has arrived at the conclusion that pediculi are provided with a sacking apparatus, or haustellum, as originally suggested by Swammerdam, and not with a mouth and mandibles, as has been commonly supposed. Such being the anatomy, it is obvious that the pediculus does not bite, but, insert- ino- the haustellum into a follicle, obtains blood by a process of sucking, producing a lesion which must be regarded in the light of a minute hemorrhage. This view is entertained also by Tilbury Foxf and others, and is without doubt correct. The secondary lesions are usually conspicuous, and are the effects of scratching upon the skin. The longer the affection has existed, and the more numerous the pediculi are, the more marked will these lesions be. The attacks of the parasite, especially in the case of pediculi capitis and corporis, bring about a peculiarly irritable state of the skin which give? rise to an irresistible desire to scratch. As a consequence, the act is indulged in, at first to a slight extent, but later to an inordinate degree, so that in the course of a few weeks the surface is, as a rule, markedly ex- coriated and lacerated. In certain subjects, in addition to the excoriations, ecthymatous pustules are produced. The amount of pigmentation varies with the duration of the affection, and with other circumstances. Diagnosis.—The pediculi may always be found, if suflEicient care be taken to discover them. Frequently they are few, when con- siderable research and close observation may be required for their detection. When violent itching exists in any case without marked eruption, the possibility of their presence should always be enter- tained and an investigation made. Pediculosis Capitis.—They are less liable to escape notice here than upon other regions of the body. The ova, or nits, which may be recognized even at a distance, serve as a diagnostic mark. * Zeitschrift fiir Wissenscliaftliche Zoologie, Bd. xiv. and xv. t Niiturhistorisk Tidsskrift, Ser. 3, vol. iii., Copenhagen, 1864-65; for translation, sec Annals and Magazine of Natural History, Ser. 3, vol. xvii., 1866. J Loc. cit., p. 413.