LAMINITIS AND NAVICULAR DISEASE. 697 
is congestion of the feet—a state that I often meet with asso¬ 
ciated with an unhealthy condition of mucous membrane, 
most generally that of the intestinal canal. Are we to think, 
for a moment, that what is plainly the result of accidental 
error, perhaps in the feeding, is due to something undefined 
and obscure in its nature, as you describe in the first part of 
your letter ? You know my views upon what is termed 
metastasis—that such an occurrence as a translation or trans¬ 
ference of this disease from one part to another does not take 
place. In my opinion it is simply an extension of diseased 
action; that the skin and mucous membrane, being con¬ 
tinuous and analogous, and the laminae of the feet are 
folds of the derma, and these folds participate in the general 
irritation of the mucous membrane through the medium of 
the skin, and being confined within the horny box of the 
feet, this confinement prevents swelling, and pain, most 
violent and acute, is the result. Let the mucous membrane 
primarily affected be restored to its healthy state, and you 
sometimes have a removal of the morbid action from the feet; 
but from the injury done to the laminae and sensitive sole, 
by the pressure of the horn, this does not always follow. 
Congestion of the feet arising from this cause must be 
treated as an effect of a cause existing in the mucous mem¬ 
brane; that from severe over-exertion, or some abuse of the 
foot itself in shoeing, as a disease sui generis. If congestion 
does not pass off it runs on to inflammation, and this charac¬ 
terised by its true character, that of exudation of liquor 
sanguinis, thrown out from the surface of the sensitive 
laminae and sensitive sole, giving rise to that form of foot 
termed pumice. You will generally find this to occur in 
about three days from the attack, and by carefully cutting 
down through the sole this exudation will escape. It will 
be found most -abundantly at the toe, which is due to the 
greater vascularity of this part, and to gravitation. Iii 
consequence, the sensitive and insensitive laminae are sepa¬ 
rated from each other, and the os pedis is pressed down¬ 
wards and backwards, and the crust upwards and forwards, 
causing the concave appearance of the front part of the wall; 
you have a displacement of the pedal bone, an altered con¬ 
dition of parts leading to important and grave pathological 
alterations in the osseous structure, and true ostitis now sets 
in. Let me be understood: whatever changes take place in 
the bony structure is a result of disease of the soft parts, 
resulting in exudation, in forcible displacement of the os 
pedis, by this exudation separating it from its attachments 
with the horny laminae, particularly at the toe; pressure 
xxx vn. 45 
