396 TUMOUR WITHIN THIS WINDPIPE OP A HOUSE. 
of the larynx an enlargement existed in conneetion with 
the trachea, which, upon further exapiination, was found to 
be partly on the outside of the tube and partly within it. 
The portion w'hich was external w'as situated at the supero- 
posterior part of the organ, whilst the other was within it, or 
rather between the cartilaginous rings and the transverse 
tracheal muscle. The first-named portion extended about 
six or seven inches along the back part of the trachea in a 
longitudinal direction. At its thickest part it was about 
one and a half inch in substance, its interior being of a 
dull-red colour, apparently produced by eflused blood. 
Its structure, as far as I could discover by the aid 
of the microscope, consisted simply of condensed areolar 
tissue. 
The part of the enlargement which w^as within the trachea 
extended over a greater surface, and w'as much more bulky, 
and when cut through had an appearance, and density also, 
unlike those of the other portion. It cut with a hard, jerking 
sensation, and was of a light bluish-gray colour. Examined 
with the microscope, I detected the following elements in its 
composition, viz., simple fibrous tissue, fibro-plastic tissue, 
elongated cells, and large nucleated cells—cancer-cells, I 
suppose. I venture to designate this portion of the deposit 
as semi-malignant in its character. During the last two or 
three weeks of the animaPs life it, no doubt, had increased 
rapidly. The muscle alluded to, within the trachea, was 
paler than natural, and much attenuated; but the mucous 
membrane which covered the deposit was in no way, as far 
as I could detect, involved. 
The question I shall briefly consider is, upon what did the 
disease primarily depend ? The redness at the back part and 
centre of the tumour w^ould suggest the idea that it was caused 
by external violence, and such, I think, w'as the case. There 
were, however, no marks on the skin of the horse’s neck to 
indicate such injuiy; nevertheless I can conceive that, by his 
coming in contact with some hard substance, the mischief 
could have been produced without leaving any mark on the 
skin. 
The non-malignant part of the enlargement, viz., the por¬ 
tion outside the trachea, can easily be supposed to have been 
produced in this w'a}^; but why the morbid growth within 
should have been of a different character I am unable to 
state. I believe, however, that it is not uncommon, when 
a part has been injured by a blow, after some time has 
elapsed, for malignant growths to originate. The develop¬ 
ment of such products for a time will appear to be slow, but 
