formula. Such an analysis indicated
a molecule made up of several hundred atoms. Chemists did not, however,
look with much confidence upon these results, and it is not surprising
that there was no very close agreement among them as to the number of
atoms in this supposed complex molecule. Moreover, from the very first,
some biologists thought protoplasm to be not one, but more likely a
mixture of several substances. But although it was more complex than any
other substance studied, its general characters were so like those of
albumen that it was uniformly regarded as a proteid; but one which was
of a higher complexity than others, forming perhaps the highest number
of a series of complex chemical compounds, of which ordinary proteids,
such as albumen, formed lower members. Thus, within a few years
following the discovery of protoplasm there had developed a theory that
living phenomena are due to the activities of a definite though complex
chemical compound, composed chiefly of the elements carbon, oxygen,
hydrogen, and nitrogen, and closely related to ordinary proteids. This
substance was the basis of living activity, and to its modification
under different conditions were due the miscellaneous phenomena of life.

(c) _Significance of Protoplasm_.--The philosophical significance of
this conception was very far-reaching. The problem of life was so
simplified by substituting the simple protoplasm for the complex
organism that its solution seemed to be not very difficult. This idea of
a chemical compound as the basis of all living phenomena gave rise in a
short time to a chemical theory of life which was at least tenable, and
which accounted for the fundamental properties of life. That theory, the
_chemical theory of life_, may be outlined somewhat as follows:

The study of the chemical nature of substances derived from living
organisms has developed into what has been called organic chemistry.
Organic chemistry has shown that it is possible to manufacture
artificially many of the compounds which are called organic, and which
had been hitherto regarded as produced only by living organisms. At the
beginning of the century, it was supposed to be impossible to
manufacture by artificial means any of the compounds which animals and
plants produce as the result of their life. But chemists were not long
in showing that this position is untenable. Many of the organic products
were soon shown capable of production by artificial mea