to state his theory of the structure of germ-plasm, but an
illustration may present fairly clear all that is of special
importance to us.

The molecules of germ-plasm are grouped in units, and these in an
ascending series of units of continually increasing complexity,
until at last we find the highest unit represented in the nucleus of
the germ-cell. 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,