Two
I
The Embryo at the
Wound
Reneration was largely forgotten for a century. Spallanzani had been
so thorough that little else could be learned about it with the techniques
of the ime. Moreover, although his work strongly supported epigenesis,
its impact was lost because the whole debate was swallowed up in the
much larger philosophical conflict between vitalism and mechanism.
Since biology includes the study of our own essence, it's the most emo-
tional science, and it has been the battleground for these two points of
view throughout its history. Briefly, the vitalists believed in a spirit,
called the anima or elan vital,
that made living things fundamentally
different from other substances. The mechanists believed that life could
ultimately be understood in terms of the same physical and chemical
laws that governed nonliving matter, and that only ignorance of these
forces led people to invoke such hokum as a spirit. We'll take up these
issues in more detail later, but for now we need only note that the
vitalists favored epigenesis, viewed as an imposition of order on the
chaos of the egg by some intangible "vital" force. The mechanists fa-
vored formation. Since science insisted increasingly on material expla-
nations
for
everything,
epigenesis
lost
out
despite
the
evidence
of
regeneration.
Mechanism dominated biology more and more, but some problems
remained. The main one was the absence of the little man in the sperm.
Advances in the power and resolution of microscopes had clearly shown
that no one was there. Biologists were faced with the generative slime