4. HORMONES AND BEHAVIOR
235
steroids, estrogens were used more commonly than androgens. For the
most part when estrogens were administered to genetic males, a temporary feminization of behavior (388, 410, 411) or a weaker effect—
better thought of as a lessening of the masculine responses—was reported (31, 412, 413). The behavior of one estrogenized bird (414) is
not reported as being affected by the treatment. Premature attempts to
crow are said to have followed injections of testosterone propionate into
eggs of genetic females (415). Pincus and Hopkins (410) dipped eggs
into testosterone, 17-methyltestosterone, progesterone, and A
5
-pregnenolone and its glucoside. They reported simply that masculinization of the
female was not accomplished as easily or to the same extent as feminization of the male.
It is clear that the results which followed the administration of
estrogenic and androgenic substances into embryonic fowl do not give
complete support to the suggestion that gonadal hormones present at
that time have an organizing action on the tissues mediating sexual
behavior in the adult. On the other hand, no data we have found would
lead us to reject this possibility.
Consideration of the numerous reports on the effects of gonadal
steroids administered before birth or hatching to representatives of four
of the five large vertebrate phyla prompts the suggestion that in all a
period exists during development when larval, embryonic, or fetal
gonadal substances do much to determine the character of sexual behavior displayed during adulthood. For the two mammals for which
information exists the evidence seems clear; for members of the other
phyla it must be considered presumptive. If differences exist, suggesting
an evolutionary trend (cf. Section X), they are not apparent from the
data presently at hand. What seems justified are the hypotheses that
this organizing action is more complete in some individuals and in some
species than in others, and that the degree to which a pattern of behavior
is displayed by the two sexes and the degree to which there is dimorphism in the responsiveness of adults to estrogens and androgens
(9) vary accordingly. Investigation of the possibility would be time
consuming, but when consideration is given to the importance of the
character of the soma or substrate on which the hormones act for the
behavior they elicit, more than an ordinary effort would seem to be
justified.
Identification of the tissues on which these hormones act would be
desirable. Presumably they are neural (33). This much had previously
been suggested by Harris (416) in another context. Noting from the
work of Pfeiffer (417) that prepuberal testis grafts in female rats produce a constant estrous state after puberty, and that ovaries grafted
235
steroids, estrogens were used more commonly than androgens. For the
most part when estrogens were administered to genetic males, a temporary feminization of behavior (388, 410, 411) or a weaker effect—
better thought of as a lessening of the masculine responses—was reported (31, 412, 413). The behavior of one estrogenized bird (414) is
not reported as being affected by the treatment. Premature attempts to
crow are said to have followed injections of testosterone propionate into
eggs of genetic females (415). Pincus and Hopkins (410) dipped eggs
into testosterone, 17-methyltestosterone, progesterone, and A
5
-pregnenolone and its glucoside. They reported simply that masculinization of the
female was not accomplished as easily or to the same extent as feminization of the male.
It is clear that the results which followed the administration of
estrogenic and androgenic substances into embryonic fowl do not give
complete support to the suggestion that gonadal hormones present at
that time have an organizing action on the tissues mediating sexual
behavior in the adult. On the other hand, no data we have found would
lead us to reject this possibility.
Consideration of the numerous reports on the effects of gonadal
steroids administered before birth or hatching to representatives of four
of the five large vertebrate phyla prompts the suggestion that in all a
period exists during development when larval, embryonic, or fetal
gonadal substances do much to determine the character of sexual behavior displayed during adulthood. For the two mammals for which
information exists the evidence seems clear; for members of the other
phyla it must be considered presumptive. If differences exist, suggesting
an evolutionary trend (cf. Section X), they are not apparent from the
data presently at hand. What seems justified are the hypotheses that
this organizing action is more complete in some individuals and in some
species than in others, and that the degree to which a pattern of behavior
is displayed by the two sexes and the degree to which there is dimorphism in the responsiveness of adults to estrogens and androgens
(9) vary accordingly. Investigation of the possibility would be time
consuming, but when consideration is given to the importance of the
character of the soma or substrate on which the hormones act for the
behavior they elicit, more than an ordinary effort would seem to be
justified.
Identification of the tissues on which these hormones act would be
desirable. Presumably they are neural (33). This much had previously
been suggested by Harris (416) in another context. Noting from the
work of Pfeiffer (417) that prepuberal testis grafts in female rats produce a constant estrous state after puberty, and that ovaries grafted