shall develop
depends sometimes on internal, sometimes on external causes, according
as the specific determinant has arisen phylogenetically through the
action of internal or external causes. Climatic and nutritive influences
especially affect the appearance of indefinitely developing
determinants. Just so, when a determinant may develop repeatedly (as is
so common in the plant kingdom) it depends especially on nutrition
whether the corresponding phenomenon is repeated at intervals of greater
or less length. A weakened determinant is sometimes temporarily
developed by the operation of a definite stimulus.

If the integrity of the organism sustains an injury in consequence of
abnormal interferences, determinants develop exceptionally at unusual
points. The process is induced by accumulation of nutritive matter and
by external stimuli under the force of necessity, to which the injured
organism is sensible.

14. ESSENTIAL NATURE OF THE ORGANISM.

The essential nature of a thing is the sum total of its causes and
effects. Organisms arise from a germ cell which consists of idioplasm
and in turn they produce like germ cells. Their nature depends also on
their idioplasm, _i.e._, on the sum total of their idioplasmic
determinants. Observation of organisms, even in their fullest life
history, gives us an imperfect and even false conception of their true
nature. This is because observation reveals only the outer gross
characters, and even these in a modification dependent upon accidental
effects of nutrition, and does not reveal the finer characters founded
in molecular physiology and morphology, and especially the characters
latent in the idioplasm.

For the examination of idioplasmic differences we are restricted to
visible characters. Hence a knowledge of the nature of an organism
presupposes a complete investigation of its characters in their
succession during the whole ontogeny. The results must, however, be
tested and completed by comparison with other organisms and by the most
comprehensive experimental procedure, possible, (as by culture under
various conditions, and crossing with nearer and more remote relatives).
The characteristics of nutrition varieties and accidental crosses must
be separated from specific characteristics by experimental procedure,
and latent determinants must be brought out by the same means.

15. REPRODUCTION, AND RELATION BETWEEN PARENTS AND OFFSPRING.

Reproduction is nothing more tha