hether the fault is in the cell
proper, the conducting media, or the central center, we are unable to
say. It is certainly not due to any vascular disturbances, as the skin
shows no vascular changes.

White spots on the nails are quite common, especially on young people.
The mechanic cause is the presence of air between the lamellae of the
affected parts, but their origin is unknown. According to Crocker in
some cases they can be shown to be a part of trophic changes.
Bielschowsky records the case of a man with peripheral neuritis, in
whom white spots appeared at the lower part of the finger-nails, grew
rapidly, and in three weeks coalesced into a band across each nail a
millimeter wide. The toes were not affected. Shoemaker mentions a
patient who suffered from relapsing fever and bore an additional band
for each relapse. Crocker quotes a case reported by Morison of
Baltimore, in which transverse bars of white, alternating with the
normal color, appeared without ascertainable cause on the finger-nails
of a young lady and remained unchanged.

Giovannini describes a case of canities unguium in a patient of
twenty-nine, following an attack of typhoid fever. On examining the
hands of this patient the nails showed in their entire extent a white,
opaque, almost ivory color. An abnormal quantity of air found in the
interior of the nails explains in this particular case their impaired
appearance. It is certain that the nails, in order to have admitted
such a large quantity of air into their interior must have altered in
their intimate structure; and Giovannini suggests that they were
subject to an abnormal process of keratinization. Unna describes a
similar case, which, however, he calls leukonychia.

Plica polonica, or, as it was known in Cracow--weicselzopf, is a
disease peculiar to Poland, or to those of Polish antecedents,
characterized by the agglutination, tangling, and anomalous development
of the hair, or by an alteration of the nails, which become spongy and
blackish. In older days the disease was well known and occupied a
prominent place in books on skin-diseases. Hercules de Saxonia and
Thomas Minadous, in 1610, speak of plica as a disease already long
known. The greater number of writers fix the date of its appearance in
Poland at about the year 1285, under the reign of Lezekle-Noir.
Lafontaine stated that in the provinces of Cracow and Sandomir plica
formerly attacked the peasantry, beggars, and Jews in the pr