264 
A Cause of Appendicitis 
Davaineci urogalli (Modeer). 
Almost all grouse contain D. urogalli, only a very small percentage 
being free from it. Although the body is large the head is extremely 
small but capable of expanding and contracting. Its average diameter 
may be put at about 0T6 mm. This head is provided with a pro- 
trusible rostellum which bears a double crown of very minute hooks, 
about 6'7 g in length. There are also four well-developed suckers 
each bearing a large number of hooks varying from 6'6 g down to half 
that size. In both cases the hooks are bent and are very sharply pointed, 
thus the whole forms an admirable weapon for injuring the mucous 
layer of the alimentary tract. 
We have not as yet found that in the grouse D. urogalli has set up 
any very marked lesions or that it has caused very serious disease, but 
that at times it is capable of doing so seems most probable from analogy 
with a closely allied species which causes the so-called “nodular disease” 
of the intestine so fatal to poultry. This is caused by a closely allied 
tapeworm D. echinobothrida 1 (Megnin, 1880) which in many respects is 
very like D. urogalli. Piana (1880) has figured transverse sections of the 
intestinal wall of a fowl which was infested with this species 2 and he 
shows how the tapeworm heads burrow right through the mucous lining 
of the intestine, entirely breaking its continuity, and come to rest in 
large vesicles filled with an exudate in the muscular sheath of the wall 
just below the serosa. 
Moore (1895) has given a full account of the disease associated with 
these nodules, which vary in size from being scarcely visible to having 
a diameter of 4 mm. Moore states that they are either circular or 
lenticular and over the larger ones the mucosa sloughs leaving 
small ulcerated depressions. These also contain an exudate, a greenish- 
yellow necrotic substance and surrounding this a thin layer of in¬ 
filtrated tissue. The smaller nodules contain a more purulent sub¬ 
stance. His sections showed, as did Piana’s, that the heads of the tape¬ 
worms had penetrated the mucous membrane and were situated in 
different layers of the intestinal wall. Though more difficult to detect 
in the larger and therefore older nodules they were almost invariably 
1 Ransome (1905) regards this species as distinct from D. tetragona, a common 
parasite of fowls, partly on the ground that it causes disease and B. tetragona 
does not. 
2 He called them Taenia botrioplitis but it is the same species. 
