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Re: Function Talks at Ostrom Symposium

Stewart, Dwight wrote:
>            Thanks Toby.  Having read the replies to this & due to the fact
> that my Maint guys are busily disassembling a torordial orifice ATT,  I am 
> wondering
> about what Allan
>         proposed.  By that I mean, perhaps some transitional structure could
> have developed
>         that would allow preforation of the diaphragm in such a way that
> breathing could
>         still be accomplished.  We do this with a slit valve in controlled
> pressure systems
>         all the time.  Basically, a biological slit valve system could be
> fairly easy to evolve.
>         One simply needs a axis that can allow apperture of a reasonable
> degree, a power
>         source (pneumatic works fine) and a sealing surface for the baffle
> to fit into when
>         the slit valve is closed (and thus sealed).  Nature uses
> differential pumping in other
>         organs, why not the pulminary?  Of course, this (too) is
> speculative.  Since I think
>         nature normally comes up with ideas a tad ahead of us, I wonder if
> there isn't
>         an extant animal out there that uses this method of breathing?
>         Dwight

This sounds like a heck of a good idea.  The valve would have to be fairly 
sturdy, but 
not impossibly so.  As I think I mentioned in another post, the transition 
problem is  
less acute for small critters, but your solution would permit a more direct 
at some larger size -- maybe about the size of Archyopteryx!  Unfortunately I 
most of my detailed notes on avian respiration some time ago.  However, I have 
recollection that some such valve may still exist, although it serves a 
different function in modern birds, shunting incurrent air to the air sacs and 
preventing excurrent air from getting to the air sacs.  I'll see if anything 
the purge.

Dunno if you were on the list a couple of years ago, but there was a time when 
Ruben's ideas seriously, let alone agreeing with him, made life ... 
interesting.  As a 
result of uncontrolled predation, his students became extinct on the list so 
far as I 
know.  However, I'll see if I can get some comment.

  --Toby White