516 DISEASE IN WILD MAMMALS AND BIRDS 
obtained from previous deaths in the same group or 
enclosure. Thus, for example, a sickly monkey would be 
suspected of having tuberculosis or early osteomalacia, 
whereas no suspicion of these diseases would fall upon 
the marsupials. The same position would be assumed if a 
dove and a heron were out of condition. 
In so far as enclosures are concerned, the matter is 
somewhat different. "Whenever a case of tuberculosis 
occurs in a cage, the remaining specimens if any are 
removed and the place cleaned by soap and water and 
disinfectant and paint. The naked flame from a blast 
lamp is used when possible. Out-of-doors enclosures are 
vacated, spread with lime and allowed to lie fallow for as 
long a time as practicable. These methods have been in the 
main successful in clearing a cage of the disease, and all 
our experience demonstrates the effect of cage hygiene 
and the selection of non-infective replacements. A few 
places such as those occupied by doves and guans have 
not been freed of infection, if one judge by its appearance 
when new specimens are placed in them, but they may of 
course be due to the infection from elsewhere. The his- 
tory of seven years in the new bird house where the. 
hygienic conditions are excellent, seems to indicate that 
a cage thoroughly cleaned is no longer a source of danger, 
and that a repetition of tuberculosis in such an enclosure 
is due to its importation with new exhibits. 
The spread of the disease to nearby cages seems to 
depend upon two factors. If the number of cases has 
been large and the infection virulent, immediately adjoin- 
ing cages are involved, but the tendency to spread is 
directly proportional to the proximity of orders or 
families that have a high susceptibility for tuberculosis. 
This second factor seems to be the more important and 
is illustrated by our experience in one corner of the new 
bird house. In this area are exhibited certain doves and 
pheasants, among which are many cases, while the pas- 
serine varieties nearbv are little affected. So too in the 
