joe casserly wrote:
> If Eisenia foetida gets cut in half does either, neither, or one
> half survive?
I think the answer is "It depends on the distance of the cut from the
anterior end". If the distance is very short, only the posterior
fragment would survive and regenerate some (not all) of the lost
head segments; if the distance is long, only the anterior fragment
would survive and regenerate posteriorly; if the distance is short but
not too short, both the fragments might regenerate the lost part to a
certain extent and survive.
Read the following papers,
Moment, G. B. (1946) A study of growth limitation in earthworms. J.
Exp. Zool. 103, 487-506.
Moment, G. B. (1949) Segment frequencies in anterior regeneration in
the earthworm, Eisenia foetida. J. Exp. Zool. 111, 449-456.
and if you would like to know more,
Berrill, N.J. (1952) Regeneration and budding in worms. Biological
Reviews 27, 401-438.
By the way, I am working with a potworm, Enchytraeus japonensis, who
reproduces asexually by dividing the full-grown body into about 10
fragments. Each fragments regenerate the head and tail in 4 days, grow
fully in another 10 days, and fragments again.
National Institute of Sericultural and Entomological Science,
Tsukuba, Ibaraki 305-8634, Japan
<myohara at nises.affrc.go.jp>
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