EIGHTH ANNUAL REPORT. dL 
The question of the necessity of mechanical or forced-draft sys- 
tem for this building may be considered settled by conclusive 
evidence that it is not necessary. The supply of outside air 
that is continually brought into the building, warmed over coils 
of hot-water pipes, and delivered both into the large cages and the 
auditorium, finds its way out of the top of the cages and the 
main hall by a system of upper currents, which carries away what 
would otherwise be objectionable animal odors. 
The great decrease in the number of cases of tuberculosis 
among the primates may fairly be regarded as evidence that the 
air supply of the Primates’ House is very nearly what it should be. 
During the year 1902, and immediately following the opening of 
this building, the animals within it were subject to the conditions. 
under which they entered it, and the death-rate from tuberculosis 
was as heavy as it usually is in such collections. During the first 
year of the building’s use, the animals which entered the Pri- 
mates’ House with tuberculosis disappeared by death, and were re- 
placed by healthy animals. The mortality records of 1903 show 
a decrease in the death-rate of the primates of nearly fifty per 
cent., bringing the total for the year down to a comparatively 
small number. | 
In Europe it is a common practice to keep all orangs and 
chimpanzees behind glass. Our policy has been to keep nothing, 
save marmosets, behind glass, and to give the anthropoid apes 
as much fresh air as they can stand without contracting severe 
colds. In fact, in comparison with the views of some European 
authorities respecting the air supply of anthropoid apes, we have 
gone to the opposite extreme, and prefer to furnish to the orangs 
and chimpanzees a supply of air so cool and fresh that occasion- 
ally it produces a head cold, rather than weaken the lungs of 
those creatures by a constant high temperature, and consequent 
diminution of vitality. 
All the large cages of the Primates’ House have proven con- 
ducive to great activity on the part of their living inhabitants. 
The only cases of cage paralysis (three in number) have occurred 
in the small side cages. It must be borne in mind, however, that 
in every large collection of primates there must be a liberal num- 
ber of small cages for the use of timid animals that fare badly in 
mixed company, and also for quarrelsome individuals that will 
not live peaceably in the cages that are devoted to groups. 
The lignolith floors of our cages have proven of extreme value 
in the matter of cleanliness, and the manner in which that mate- 
rial has been applied to connect the floor with the lower portions. 
