510 DISEASE IN WILD MAMMALS AND BIRDS 
at regeneration. Few vessels show perivascular fibrous change. One 
tubercle seen. 
Anseres. These birds present no especial features so 
far as percentage or organic incidence are concerned. 
The individuals are mostly geese and swans, ducks being 
somewhat more often affected by mycosis than by tubercu- 
losis. However, both these diseases tend to assume the 
nodular type in Anseres so that the diagnosis should be 
supported by bacteriological discovery of the respec- 
tive organisms. 
Struthiones. The marked feature of this order is 
the prominence of the isolated and confluent nodules 
in the lungs, of apparently greater age, certainly of great 
size, than similar lesions in the abdominal viscera. Case- 
ation of the avian variety is well illustrated in these 
birds. The thyroid body was involved in two of the three 
cases, the ovary in one. The representatives of the 
Crypturi, two tinamous, came at the same time and lived 
only a few months. Miliar}^ tuberculosis of the small pre- 
caseous variety was the form exhibited by both specimens. 
Histology of the Tuberculous Lesions. 
The initial and characteristic unit of tuberculosis, the 
miliary tubercle, seems to be constructed upon the same 
general principles in all cases of the disease and in 
all members of the zoological groups in our study and in 
a manner entirely comparable to that well known for man 
and for the domestic animals. There are, however, cer- 
tain minute differences which are interesting and may at 
some time become important. It is customary to speak 
of the bovine tubercle and of the human variety, but there 
are also slight variations of the microanatomy of each of 
these, while one may find on occasion a tubercle of the 
human type in a cow and vice versa. Not all the domestic 
animals show the bovine form, although in sheep and 
swine it is approximated very closely. In the horse there 
is much greater tendency to a central softening and 
