NINTH ANNUAL REPORT. 139 
Confinement in the smaller cages apparently offers some predis- 
position to the disease, since we have observed more cases devel- 
oping in the smaller and darker side compartments than in the 
larger, more airy and better lighted ones. It is interesting to 
note in this connection that there has never been a single case 
in the large lemur cage, which is situated in the main corridor 
of the Primates’ House in the New York Zoological Park, and 
which receives a great abundance of sunlight during a large part 
of each day. In this cage the conditions much more nearly ap- 
proximate the normal habitat of the primates than we are able 
to afford in the other portions of the building. 
Age appears to play no definite factor in the production of the 
disease as we have seen it; though, as stated above, the time in 
captivity does seem to be an important consideration. 
The question of possible primary haemic conditions must not 
be neglected, particularly as the disease apparently occurs most 
commonly, under conditions in which we might naturally expect 
a greater or lesser degree of anaemia. We believe that primary 
anaemia is not a frequent introductory condition, though sec- 
ondary anaemias are doubtless frequently present in the early, as 
well as the later, stages of the disease, but apparently not as an 
essential primary inductive agent. 
SYMPTOMS. 
While there are no positive premonitory symptoms which are 
characteristic of this malady, still there are certain signs, the 
appearance of which will justify a provisional diagnosis. One 
of the first symptoms manifested is that the subject becomes less 
active than usual, instead of running and leaping about from 
swing to swing, it sits on the floor or isolates itself in some far 
corner of its cage and takes very little interest in its surround- 
ings except at feeding time; for the appetite generally remains 
good up to the later or terminal stage of the disease. 
Gradually a noticeable stiffness is apparent when the animal 
moves about. This stiffness is most marked in the posterior 
extremities and generally progresses quite rapidly. During this 
stage, the animal is apparently free from pain, but of this one 
cannot feel sure, since we have observed that, as a rule, monkeys 
can stand considerable pain without any external manifestation 
of suffering. Later the movements of the animal become quite 
cumbersome, its actions resembling those of animals suffering 
from rheumatism. If the animal is closely examined, even at 
