Dear WW: I can't remember whether what I described was something I saw in dissecting a pigeon,
or a diagram used as study aid. Anyway, the point was that sir traveled rapidly though lung tissue
in both directions. So far I haven't found anything good on internet. I did find one URL that you
might like to browse through.http://home.earthlink.net/~maalatt/science.html#resources.
Didn't see anything about money being charged.