GREAT NAUTILUS. 
mient. But, observes Knorr, as these tubes are 
•^o narrow, it is not to be credited that an ani- 
mal, whose flesh is externally very cartilaginous 
and rough, can possibly find a passage ; it there- 
fore becomes necessary that we should suppose 
these chambers destined to some other use. Rum- 
phius, indeed, says that a certain blood-vessel 
of the animal passes through these tubes, and 
traverses all the chambers, quite to the centre 
of the shell, or last chamber, where it is at- 
tached ; and that this point is, also, the only 
one where the animal adheres to the shelL 
However, contends Knorr, as Nature produces 
nothing without a reason, and it is consequently 
certain that so many chambers must have their 
use ; we may presume that this animal, which 
can, apparently, like the worm tribes, render 
itself larger or smaller, according as it wishes 
to advance or to retreat, penetrates by that 
blood-vessel into the interior of the chambers 
as much as possible, those parts being moistened 
by the flesh sufficiently to admit it's progress, 
or the blood-vessel distending itself fills the 
chamber, and thus enables the animal either to 
fix itself more firmly in it's shell, or better 
conceal itself in the depths of it's retreat, that 
it's ^ 
