Horny 'Excrefcences of the Human Body ror 
progrefs it exactly refembled them, remaining ftationary for a 
long time, and then coming forwards to the Ikin ; and the 
horn being much fmaller than the tumor previoufly to the for- 
mation of the horn, is a proof that the tumor muft have burft, 
and difcharged its contents. 
From the foregoing account it muft appear evident, that 
thefe horny excrefcences are not to be ranked among the ap- 
pearances called lufus naturae : nor are they altogether the pro- 
duct of difeafe, although undoubtedly the confequence of a 
local difeafe having previoufly exifted ; they are, more properly 
fpeaking, the refult of certain operations in the part for its own 
reftoration ; but the actions of the animal oeconomy being 
unable to bring them back to their original ftate, this fpecies 
of excrefcence is formed as a fubftitute for the natural cuticu- 
lar covering. 
To explain the manner in which thefe horns are formed, it 
will be neceffary to confider the nature of incyfted tumors a 
little more fully ; and in doing fo we fhall find, that this par- 
ticular fpecies does not differ in its principle, nor materially in 
its effefts, from many others which are not uncommonly met 
with in the human body, as well as in thofe of many other 
animals, which, as they are more frequent in their occurrence, 
are alfo much better underftood. 
Incyfted tumors differ exceedingly among themfelves, both 
in the nature of their contents, and in their progrefs towards the 
external lurface of the body. Many of them have no reference 
to our prefent purpofe ; it is only the more indolent kind to 
which I mean now to advert :: fome of thefe, when examined, 
are not found to contain a fluid, but a fmall quantity of thick, 
curd-like matter, mixed with cuticle broken down into fmall 
parts, and upon expofing the internal furface of the cyft, it is 
found 
