348 DISEASE IN WILD MAMMALS AND BIRDS 
by erosion, were flattened. It is perhaps worthy of 
mention that this old and familiar animal was the occu- 
pant of the same enclosure, floored with cement, for over 
thirty years, conditions which might be partly instru- 
mental in the arthritic changes as well as in the flattening 
of articular surfaces. 
The Ungulata frequently suffer with wounds, ulcers 
and abscesses about the lips, nose, and soft tissues of the 
jaws which may at times be confusingly like actinomy- 
cosis. This disease we have seen in gazelles and tapirs 
but have had to exclude it in several other members of this 
order. A number have come to autopsy with osteitis of 
the lower mandible, some evidently traumatic in origin, 
others probably due to infection via the teeth. Figure 44 
represents the jaw bone of an Isabelline gazelle {Gazella 
Isabella) suffering with a rarefying osteitis from a root 
abscess, and illustrates well the possibility of focal infec- 
tion from this source. 
Degenerative Skeletal Diseases. 
While the foregoing instances of disease in the osseous 
system are interesting examples of individual patho- 
logical lesions, they are insignificant in comparison with 
the forms of bony change kno^\^l under the names of rick- 
ets, osteomalacia, osteogenesis imperfecta and the like- 
systemic conditions which are chiefly degenerative but 
have certain evidences of inflammation in addition. The 
modern knowledge of tJie first two named is so far from 
complete that it cannot be said that there is any certainty 
of their identity. Indeed there seem, to be some reasons to 
think that there is more than one variety of rickets, that all 
cases are not dependent upon the same cause, and that in 
essence it is the same process as osteomalacia, the latter, 
however, occurring at a later age. We shall show that in 
the same order, Primates, both diseases may occur in 
animals fed upon the same diet, and that one family tends 
to have one disease, another family the other. 
