NINTH ANNUAL REPORT. I39 



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 Xew 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 nearlv ap- 

 proximate the normal habitat of the primates than we are able 

 to aft'ord 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 primarv 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 stift'ness 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 suft'cring 

 from rheumatism. If the animal is closelv examined, even at 



