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Tyler, John Mason, 1851-1929

"A Brief History of His Origin and Development through Conformity to Environment; Being the Morse Lectures of 1895"

This grouping of molecules in units of increasing
complexity is like the grouping of the men of an army in companies,
regiments, brigades, divisions, etc.
To form the somatoplasm of the different tissues of the body, this
complicated organization breaks up, as the egg divides, into an
ever-increasing number of cells. First, so to speak, the corps
separate to preside over the formation of different body regions.
Then the different divisions, brigades, and regiments, composing
each next higher unit, separate, being detailed to form ever
smaller portions of the body. The process of changing germ-plasm
into somatoplasm is one of disintegration. The germ-plasm
contains representatives of the whole army; a somatic cell only
representatives of one special arm of a special training. Germ-plasm
in the egg is like Humpty-Dumpty on the wall; somatoplasm, like
Humpty-Dumpty after his great fall.
I use these rude illustrations to make clear one point: Germ-plasm
can easily change into somatoplasm, but somatoplasm once formed can
never be reconverted into germ-plasm, any more than the fallen hero
of the nursery rhyme could ever be restored.
The germ-plasm is, according to Weismann, a very peculiar, complex,
stable substance, continuous from generation to generation since the
first appearance of life on the globe.


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