paper on the "Rediscovery of the Unique," H.G. Wells emphasized the
unique quality of the individual, and how, in spite of the cleverest
devices of classification, living things ultimately escaped the
classifying net by virtue of their tendency forever to vary.

The individual is unique. Yet when all is said and done, the fact
remains that between individuals there is resemblance, and among them
variation. What is the reason for their resemblances and what is the
cause of their variation?

The conception of a particular chemical make-up of the individual,
statable and relatively controllable in terms of the internal
secretions, supplies a more rational and satisfactory method
of approach to the problem than any so far suggested as far as
vertebrates are concerned at any rate. In effect, the differences
between individuals may fundamentally thus be grouped among the
differences which distinguish other chemical substances. The
difference between water, technically known as hydrogen monoxide,
and the antiseptic fluid labeled hydrogen dioxide lies wholly in the
possession by the latter of an extra atom of oxygen in its molecules.
All the peculiarities and qualities by which hydrogen peroxide is
separated from water are referred to that additional quantum of
oxygen. So the diversity of constitution and appearance of two
brothers, alike in that they have inherited the same internal
secretion trends, may be traced to the superiority of the pituitary of
the one over the other.

Variation and resemblance are large issues, crucial material of the
science of biology upon which much has been thought and written. That
the proportion of the endocrines determines variation and resemblance,
heredity and evolution is a hypothesis advanced, supported by a large
amount of facts, and capable of the most interesting experimental
verification and observation. If a child resembles particularly either
of its parents, grandparents or relatives, there is good reason for
believing that it is because their endocrine formulas are very much
alike. When people apparently not blood-related at all resemble
one other, the same law must hold. Resemblances may be partial or
complete, and the degree will depend upon the amount and ratio of the
internal secretions involved.

The same endocrine constitutions will produce corresponding physiques,
physiognomies, abilities and characters. Deviations in endocrine type
from that of the original stock, more