aracteristics and instincts
into the female type. The growth of the male sex organs he found to be
definitely inhibited by the ovaries. He went so far as to transplant the
whole uterus and tube into the male body, where it developed normally.
One of the most interesting of his results is the observation of how the
instincts were changed along with the type of body. The feminized males
behaved like normal females toward the other males and toward females.
Likewise they were treated as normal females by the males.

It would be impossible to give here any just idea of the vast amount of
rigid scientific experimentation which has been carried on in this
field, or the certainty of many of the results. Sex is really known,
about as well as anything can be known, to arise from the chemical
causes discussed above. That is, the endocrine explanation is the
correct one.

One of the most significant results of the transplantation experiments
is the evidence that _each individual carries the fundamental bases for
both sexes_. When Goodale changed a male bird into a female as to
secondary characters and instincts by replacing one secretion with
another, he was faced with the following problem: How can a single
secretion be responsible for innumerable changes as to feather length,
form and colouring, as to spurs, comb and almost an endless array of
other details? To suppose that a secretion could be so complicated in
its action as to determine each one of a thousand different items of
structure, colour and behaviour would be preposterous. Besides, we know
that some of these internal secretions are _not_ excessively
complicated--for instance adrenalin (the suprarenal secretion) can be
compounded in the laboratory. We may say that it cannot possibly be that
the ovarian or testicular secretion is composed of enough different
chemical substances to produce each different effect.

There remains only the supposition that the female already possesses the
genetic basis for becoming a male, and _vice versa_. This is in accord
with the observed facts. In countless experiments it is shown that the
transformed female becomes like the male of her own strain and brood--to
state it simply, like the male she would have been if she had not been a
female. If we think of this basis as single, then it must _exhibit_
itself in one way in the presence of the male secretions, in another way
under the influence of the female secretions. In this way a very