EIGHTH ANNUAL REPORT. 117 



confined, but this does not seem to be well founded, since it ap- 

 pears alike in animals confined in the ordinary board-floor cages 

 of the travelling menageries, in metal cages, the floor of which 

 is covered by some soft substance, and in those which have the 

 ground as a floor. The cleanliness of quarters does not seem to 

 affect the etiological factors, for the disease apparently occurs 

 as frequently in the scrupulously kept enclosures of the New York 

 Zoological Park as in the often foul quarters of the animal deal- 

 ers. Confinement in smaller cages apparently offers some predis- 

 position to the disease, since we have observed fewer cases occur-, 

 ring in the larger, more airy, and best-lighted cages ; most of 

 the cases developing in the smaller and darker side compartments. 

 Food has apparently no effect on the disease. The mental effects 

 of restraint apparently do not act as a causative factor, for as a. 

 rule the disease occurs in those animals which take very kindly: 

 to cage life, and it does not appear more frequently in those ani- 

 mals which are most affected by confinement and restraint. The 

 mentality of the animals bears no apparent relationship to the. 

 onset of the disease. 



A few cases are found which have followed traumatism, but' 

 the instances have been so few as to almost lead one to the con-' 

 elusion that they have always been but coincidences and that in- 

 jury in reality had nothing to do with the onset. The character 

 of the food has apparently nothing to do with the causation of. 

 the disease, for at the New York Zoological Park the food is ; 

 very thoroughly inspected, and the amount and character is care- 

 fully controlled. Nevertheless it is generally admitted that the : 

 disease occurs mostly in animals which have been in captivity for 

 a considerable length of time, and animal men, who as a rule 

 are keen observers, are convinced that the cause of the disease is 

 in some way connected with the effects of captivity. 



Onset. — The first symptom generally noticed is a stiffness of 

 the lower extremities, manifested in that the animal is not as 

 quick and agile as usual and soon ceases to attempt the more dif- 

 ficult feats which the monkeys in particular are so fond of doing. 

 This stiffness is generally more evident on one side than the 

 other, and the actions of the animal resemble those of one suffer- 

 ing with rheumatism. They often continue to feed and look well, 

 but once the initial stiffness has appeared, the disease almost al- 

 ways progresses with at least observable rapidity, finally affecting : 

 both of the rear extremities. During this period the animal is. 

 apparently free from pain and, if accustomed to handling, does : 

 not resent it at this time. It is not evident that pain is produced 

 by the manipulation of the partially paralyzed extremities. fj 



