Two views on the ætiology of this disease have been brought forward up
to the present time, as far as I know—viz., that the swellings were of a
racial character and that the process was started by the larva of some
insect. With regard to the first I have only to mention that the disease
is found in Ashantis, Grunshis, Fantees, Abantas, the Ga people, etc.,
races quite different from one another, to show that this cannot be
entertained. As to the second, I have never met with evidence which
would support the idea that the disease was started by a larva. On the
other hand there is always the history of yaws and of the tumor starting
during the attack of yaws—_i. e._, during the period of eruption or soon
after. Then, again, the patients complain of pain in the nose with, in
some cases, distinct history of a sore and sometimes discharge preceding
the swelling. This might be due to some irritation or ulceration of the
nasal mucous membrane by the yaws. I have never had the opportunity of
examining any person at this stage of the disease, but in the more
developed cases I have examined the nose for marks or signs of old
ulceration, but have not found them. If, however, the nasal process of
the superior maxilla be examined a few foramina are to be seen, and
these are often joined together by a small groove indicating the
position of a bygone suture. The foramina are for small bloodvessels,
which are said to communicate with those of the mucosa of the nose. The
site of these foramina is the situation where henpuye starts, and I
venture to bring forward the theory that the causation of this peculiar
disease is due to an osteoplastic periostitis brought about by the
absorption of the poison of yaws from the nasal mucous membrane through
the small vessels (or lymphatics) keeping open the foramina which
indicate the suture above mentioned.