XII 
THE HIPPOPOTAMUS 
7 
must have far exceeded the weight to which the 
animal was accustomed. 
It is difficult to decide the limit of time during 
which a hippopotamus can remain beneath the water. 
The nostrils have the power of closing, with the 
action of valves, and the animal sinks itself with 
the lungs inflated. The blood is nourished with 
oxygen from this supply of air during immersion, 
and when the animal appears upon the surface, it 
blows out the expended air with a peculiar snort, 
accompanied by a jet of spray, very similar to 
the manner in which the whale and other cetacea 
“ spout.” 
Precisely in the same way the hippopotamus 
blows off the impure air, and again refills the 
lungs by an instantaneous effort like the cetacea; 
and by the time that the eye detects the jet of 
spray, the lungs have been emptied and again 
inflated. 
I have very frequently observed, and taken 
the time by my watch, but I have found that 
hippopotami vary in the times of total immersion. 
Five minutes is about the usual interval of 
breathing, when it becomes necessary for the animal 
to ascend for a fresh supply of air, but this depends 
upon circumstances, as the hippo can sustain ten 
minutes without fresh air, should it choose to 
remain concealed. 
If a hippopotamus has been shot at several 
times, and is only slightly wounded, it will remain 
as long as possible beneath the water, and when 
