

INAUGURAL ADDRESS. | a 
with recent observations on cell structure and cell division 
by showing that the “ karyokinetic’”’ changes in the 
nucleus might be interpreted as the optical expression 
of the activity of the inherited gemmules in the cell. 
This idea of heredity was apparently in the scientific air 
at that time, since a number of modifications of the theory 
continued to appear during the following two years leading 
up to Weismann’s very complete and elaborate theory of 
the continuity of the germ-plasma,* published in 1885. 
The central idea of this theory is very similar to that 
of Galton’s, and is that the germ cells or reproductive 
elements arise not from the body of the individual, but 
direct from the parent germ cell. Thus a living substance, 
which Weismann calls the germ-plasma, passes over from 
one generation to another—the germ cells of succeeding 
generations being related to one another very much as are 
a series of unicellular organisms, such as Amebe. 
Weismann werked out the theory so admirably, showing 
its connection with the facts and principles of Biology, 
and supported it by such powerful arguments, that it was 
at once received as an important contribution to biological 
philosophy, and has been largely discussed and pretty 
generally accepted during the last few years. The only 
difficulty which I personally feel in regard to it—and it is 
one which applies equally to all of these allied theories—is 
its aspect towards acquired characters. If the gemmules 
or the particles of germ-plasma which produce the body 
of an individual are derived, not from the body of the 
parent animals, but from their dormant gemmules or 
germ-plasma, then it is difficult to see how any characters 
in the parents, produced by such influences as use and 
disuse and the action of the environment, can be 
*“Die Continuitiit des Keimplasma’s als Grundlage einer Theorie der 
Vererbung,” Jena, 1885 ; and several other papers since. 
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