ANATOMY OF THE BEAVEK. 551 
traversing the lungs. We now know that this false ana- 
logy gave rise to many errors, and to some singularly un- 
productive experiments. 
Of the objections which may be offered to this opinion 
of the uses of the venous sinuses in aquatic animals, one 
may be urged, drawn from the apparent inadequacy of the 
means provided by nature, for the suspending of a function 
so essential to life as the oxygenation of the blood. But 
to obviate this, we may remark, that Man, who neither is 
nor can become amphibious, can yet suspend his respiration 
for a space of time nearly equal to six minutes. Now, if 
an animal in which there exists no special apparatus for 
that purpose, and aided only by the momentary congestion 
of the blood in the liver, spleen and branches of the vena 
ports?, can suspend for so long a time the function of re- 
spiration, it is not unphilosophical to suppose, that in those 
furnished with peculiar organs, such as large venous sinuses, 
and numerous venous trunks of large caliber, the same func- 
tion may be suspended for double, treble, or even quadruple 
the time, without any inconvenience to the animal. It is 
more difficult to offer the rationale of the phenomenon, and 
to explain how the collecting of blood in venous trunks and 
sinuses should enable an animal to dispense with a function, 
on the continuance of which animal life so immediately de- 
pends. 
It was very generally believed, previous to the experi- 
ments of BicHAT, that, in cases of suffocation, generally 
speaking, the first interruption to the circulation of the 
blood occurred in the lungs ; that, in consequence of this, 
it accumulated in the pulmonary artery, right side of the 
heart, and whole venous' system. To explain this distribu- 
tion of the blood after death, in cases of suffocation, some 
very erroneous mechanical theories were brought forward, 
affecting to demonstrate, that the impediments to the blood's 
3 
