226 
A. ZUNDEL. 
tion of the dressing. The same must be done at the other dres¬ 
sings, carefully watching if this new horn thus formed by the influ¬ 
ence of the medication, is not separable from the parts underneath 
by the different morbid secretions of the disease. One must then 
carefully scrape off all that is not adherent, and thin the edges, 
and the projections of all the horn which retains its soundness ; 
the caseous substance being also removed ; the same compressive 
dressing to be put on again. 
The modification in the horny secretion, and the formation of 
a layer of hardened and adherent horn, are especially great in the 
parts where podophyllous and velvety tissues exist; but are very 
slow, and surrounded with difficulties in the median and lateral 
lacunae of the frog. After ten days of treatment, one may have 
brought about a normal secretion on the whole circumference of 
the sole, on the inferior face of the os pedis, and on the promi¬ 
nent parts of the pyramidal body. But in the lacunae the altera¬ 
tion remains isolated, and resists treatment; and it often happens 
that, if neglected it may again spread and the disease reach its 
former extent. It is then the case, when the disease is limited 
to the lacunae, to add to the ingredient already in use and which 
is kept applied upon the restored parts, another stronger and 
more active agent, sometimes simple absorbent; here again it 
becomes difficult for us to advise the practitioner, the number of 
recommended drugs being very large and the result depending 
less on their natnre than in the intelligent and persisting manner 
with which it is applied. When one thinks to use caustics it must 
be done with care, to limit their action only to the thickness 
of the keratogenous tissue, and not to carry it to the destruction 
of the bone, or still worse, of the plantar aponeurosis. 
Let us glance at the drugs which have proved most successful 
in the treatment of canker : First we have the different pyrogen- 
ous preparations, especially wood tar, recommended by Bracy, 
Clark, Reynal and Bouley, and which give astonishing results. Gas 
tar, oil of cade, petroleum and soot have also been used, but with 
less advantage ; creosote and pheuic acid have often shown them¬ 
selves very useful, by penetrating easier to the base of the villosi- 
ties where the parasite resides and thus acting more regularly; 
