THE COMMUNICABLE DISEASES 507 
sucli extensive and advanced lesions as in these little 
birds. Sometimes one whole lung will be solid while its 
fellow will be half occupied by caseous material. The 
doves alone seem to approximate the Passeres in ability 
to live with so much tuberculous exudate. 
Picarise. Specimens from this order illustrate well the 
intestinal origin and distribution of tuberculosis. There 
was, among these birds, one case showing tuberculomata 
which was, because of its gross anatomy, listed as the 
pearl type. Its description is as follows : 
Lesson's Motmot {Momotus lessoni) . The region above and behind 
the right clavicle in front of the brachial plexus on the internal sur- 
face of the thorax, exterior to the first and second ribs, and on the 
internal surface of the ribs at the junctions of ribs with the alae of 
the sternum, there are many small, irregular, smooth, firm, yellowish 
white nodules varying in shape from spherical to sweet potato and 
in size from 3x3 mm. to 3 x 7 mm. These are found quite homogeneous 
on cross section. They do not resemble tubercle or mould infection 
but make one think of neuromata. There are also a few present in 
the left lateral air sacs, close to but not joining the intestine. The 
lungs are apparently normal. Histological section of the masses de- 
scribed as distributed along the nerves consist of sharply outlined but 
not well encapsulated masses made up of irregularly disposed bunches 
of large cells with vesicular nuclei in a stroma of loose connective tis- 
sue very inconspicuous in amount. There is also quite a number of 
small round cells and a few leucocytes. The large cells first described 
have the nucleus eccentric for the most part. Many of them have 
two nuclei and a few three and occasionally a giant cell is observed. 
Blood vessels have a very delicate wall and are frequently encountered 
in the centre of these masses. Atypical mitoses can be found. Here 
and there a seal ring placement of the nucleus can be found. A few 
eosinophiles are present not definitely placed. Necroses, with large 
quantities of nuclear fragments, are scattered irregularly through the 
mass. The diagnosis rests between an infectious granuloma, false 
neuroma and sarcoma. Tubercle bacilli were found by stain in great 
numbers both within and without the cells. 
Psittaci. Tuberculosis occurs in this order somewhat 
more frequently in the varieties whose habitat is the 
Eastern world, although South American birds also suffer 
from it in the characteristic manner. There seems to be 
no difference in the pathology of these two groups. Par- 
rots present very beautifully the separate solid or semi- 
