CONTRIBUTIONS TO ZOOLOGICAL PATHOLOGY. 407 
Of all the subdivisions of canine pathology there is none, perhaps, 
which has been less taken notice of than that which treats of the 
diseases of the organ of hearing ; for, with the exception of the 
very vague and barbarous terms of “external and internal canker” 
of the ear, we find no other diseases admitted or described. And 
even under this very general nosology there is nothing definite 
expressed; and whenever any case occurs of a fetid discharge 
from the ear, it is classed under this arrangement, no matter what 
the special cause may be. 
In my present communication I shall confine myself to the de- 
scription of a class of diseases of the external ears, of which little 
notice has hitherto been taken, although in practice they are by 
no means of rare occurrence ; and at a subsequent period I shall 
again revert to some other important points in connexion with 
the special pathology of this department of the organ. 
Polypoid tumours, as they are usually seen within the external 
meatus, may be the result of a morbid action in three situations : 
the first may arise from chronic inflammation of any of the tissues 
which enter into the formation of the meatus ; the second may be 
connected with a similar state of the membrana tympani ; and the 
third may be the result of chronic inflammation of the lining mem- 
brane of the walls of the tympanum, the cavity of which they first 
completely occupy, and afterwards, extending themselves along 
the external meatus, ultimately make their appearance at the en- 
trance of this tube. 
As the nature and treatment of the two latter forms of polypi 
differ from the former, and as the remarks that I shall at present 
offer specially belong to the first form, I shall, therefore, confine 
my observations to it, and again return to the second and third 
varieties, should circumstances offer. 
Polypi produced from the tissues of the meatus may be divided 
into two kinds: — first, the soft, vascular, and bleeding polypus, 
usually produced from the fibro-cartilaginous structure of the outer 
half of the tube ; and, secondly, the hard and cartilaginous polypus 
or excrescence produced from the lining membrane of its inner 
half. 
As to the first of these forms of polypi, the hcematoid, that arise 
from the external soft structure of the tube, they may be situated 
in any part of its parietes, but most commonly at its superior and 
posterior surface. In form they are generally pedunculated ; their 
surface is rough, irregular, and glistening, in consequence of being 
covered with a thin layer of mucus, which is often tinged with 
blood, especially when any degree of violence has been applied to 
the external ear, and which has also been exerted upon the tumour. 
When the tumour becomes protruded externally, it has a blood-red 
