372 
ORANG-OUTANG. 
one, or natural union of these two sacks, can occasion any detriment in the 
use of it, because we see something similar taking place in the kidneys of 
the human species, whose lower parts are not unfrequently united with each 
other in such a manner as if they constituted but one, having however se- 
parate blood-vessels, and each forming on that account a ureter, without 
being able to see, from the skeleton of the body, that any obstacle has been 
occasioned by it. I possess one of this kind in my collection of anatomical 
preparations. 
“ The Orang can, in the mean time, voluntarily swell up these sacks, or 
this united sack, whenever.it tries or attempts to press the strongly inhaled 
air outwards, and presses then the epiglottis towards the opening of the 
larynx, or bends it only a little. It can also empty them at pleasure, by 
means of the broad muscles of the neck, by those of the breast, and by the 
cucullares or monk’s-hood muscles : the Rendeer, whose air-sacks do not 
lie beneath these muscles, has received from nature two muscles, which 
originating from the tongue-bone, spread out their fibres, and surround 
the whole air-sack. 
“ We conclude from this, that in the tailed monkeys, and in the Egyptian 
monkey without tail, in which we have found a single air-sack towards the 
throat, as well as in the Orangs, who naturally have two, although some- 
times gone over into one, the air, more or less, by means of the split formed 
by the larynx, loses all its force to diffuse itself from its own accord in this 
sack or sacks. 
“ There is an apparent conformity betwixt these speaking organs and those 
of the male frog, which likewise press the air the length of the tongue, into 
two bladders, situated sideways, and presses it out again with the known 
sound, from the same openings below the tongue, by means of the muscles 
of these bladders, as I have, I apprehend, demonstrated plainly in my treatise 
on the croaking of frogs.” * 
The following marks of distinction between the Orang-Outang and man, 
have already been transcribed from Camper, by Tilesius in the appendix to 
Krusenstern’s Voyage. 
“ 1. The upper jaw of the Orang-Outang does not stand perpendicularly 
under the arch of the forehead, but makes an angle of fifty-eight degrees 
* Manuscript Translation of Camper’s Treatise on the Orang-Outang of Borneo. 
