ARSENICAL POISONING FROM SMELTER SMOKE. 
165 
elusion that the lesion began as a nodule deep in the tissues, and 
that microscopic examination of sections revealed a proliferation 
of the tissue elements. 
The writer had an opportunity of examining these lesions in 
their early stages, and observed at the beginning an appearance 
as of a superficial abrasion, from one-fourth to one-third of an 
inch in diameter, which rapidly extended laterally and became 
deeper by destruction of the tissues until the typical lesion was 
developed. There was no abscess formation and very little sup¬ 
puration in the lesions which he observed. However, even in 
the absence of microbic infection, it would not be surprising if 
some of the lesions commenced as a nodule beneath the epi¬ 
thelium; for an irritating liquid penetrating a hair follicle, a 
glandular opening or a small punctured wound would cause a 
local inflammation and a nodular swelling, and, possibly, a small 
abscess. Subcutaneous injections of arsenical liquids in horses 
often produce abscesses, even when the most rigid aseptic technic 
is followed. Therefore, in the opinion of the writer, the begin¬ 
ning of such a lesion as a sub-epidermal nodule is no more indi¬ 
cation that it is caused by infection with a microbe than that it 
is caused by the penetration of a highly irritating liquid. Neither 
is the fact of the proliferation of tissue-cells of any value in the 
diagnosis between these two etiological factors. That there was 
proliferation was evident from the fibrous floor of the ulcer, even 
without microscopical examination, but bacterial irritants are, 
certainly, not the only ones which stimulate tissue proliferation. 
In order to understand the causation and development of these 
ulcers, it is necessary to make a more serious and exhaustive 
investigation of them from various points of view. 
Historical Notes .—The first “ sore noses ” in the Deer Lodge 
Valley of which any account could be obtained, were observed 
in January, 1904, shortly after the operation of the smelter was 
commenced with the high stack. From that time up to and in¬ 
cluding 1906, they were observed each year in a large proportion 
of the horses at pasture. It was alleged by the farmers that, 
practically, the ulcerations were only seen when the horses were 
