eismann came to believe that the apportionment
of the nuclear substance, though quantitatively impartial, is sometimes
radically uneven in quality; in particular, that the first bisection
of the egg-cell, which marks the beginning of embryonic development,
produces two cells utterly different in potentiality, the one containing
the "body plasm," which is to develop the main animal structures, the
other encompassing the "germ plasm," by which the racial integrity is
[to be preserved. Throughout the life of the individual, he believed,
this isolation continued; hence the assumed lack of influence of
acquired bodily traits upon the germ plasm and its engendered offspring.
Hence, also, the application of the microscopical discovery to the
deepest questions of human social evolution.

Every one will recall that this theory, born of the laboratory, made
a tremendous commotion in the outside world. Its application to the
welfare and progress of humanity gave it supreme interest, and polemics
unnumbered were launched in its favor and in its condemnation. Eager
search was made throughout the fields of botany and zoology for new
evidence pro or con. But the definitive answer came finally from the
same field of exploration in which the theory had been originated--the
world of the cell--and the Marine Biological Laboratory was the seat of
the new series of experiments which demonstrated the untenability of the
Weismannian position. Most curious experiments they were, for in effect
they consisted of the making of two or more living creatures out of one,
in the case of beings so highly organized as the sea-urchins, the
little fishlike vertebrate, amphioxus, and even the lower orders of true
fishes. Of course the division of one being to form two is perfectly
familiar in the case of those lowly, single-celled creatures such as the
protozoa and the bacteria, but it seems quite another matter when one
thinks of cutting a fish in two and having two complete living fish
remaining. Yet this is virtually what the biologists did.

Let me hasten to add that the miraculous feat was not accomplished
with an adult fish. On the contrary, it is found necessary to take the
subject quite at the beginning of its career, when it consists of an
egg-cell in the earliest stages of proliferation. Yet the principle is
quite the same, for the adult organism is, after all, nothing more
than an aggregation of cells resulting from repeated divisions (growth
a