Tom Holroyd tomh at BAMBI.CCS.FAU.EDU
Thu Sep 19 10:49:27 EST 1991

>Jean Piaget describes an interesting case. Shelless snails
>in lakes in Switzerland generally are found in an elongated
>form in placid waters. They are capable of taking on a rounded
>form when moved to turbulent waters. This behavioural modification
>allows them to survive better in the turbulent water. According to
>Piaget, they then tend to produce offspring that have a genetically
>fixed rounded from (over numerous generations).

This is not a modification of the genotype, right?  The snails
develop a different shape depending on the environment they mature in?
In other words, the genotype has the potential for both kinds of
shell, and the environment forces one or the other to be expressed.
Or do their offspring remain rounded even in placid waters?  How
could this be passed on?  Some enzymes in the egg?  I can imagine
that, but wouldn't it be better to let the environment determine it?

Tom Holroyd
Center for Complex Systems
Florida Atlantic University
tomh at bambi.ccs.fau.edu

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