Sex (electronic resource)

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Identifier: b20442221 (find matches)
Title: Sex (electronic resource)
Year: 1914 (1910s)
Authors: Geddes, Patrick, Sir, 1854-1932.
Subjects: Sex
Publisher: New York : H. Holt and company London : Williams and Norgate
Contributing Library: Wellcome Library
Digitizing Sponsor: Wellcome Library

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on with the gonadial glandsof internal secretion which supply in a remark-able way their indispensable liberating stimuli. The secondary sex-characters are, to beginwTith, systematic characters and they ulti-mately owe their development and differen-tiation to the harmonious co-operating of theglands of internal secretion. The thesis that: All secondary sex-characters were at first specific characters,appears to us to be an exaggeration of a soundidea. There are, it seems to us, numerouspeculiarities of one sex or the other whichcannot be readily derived from specific char-acters supposed to be common to both sexes. THEORY OF SEX-DIMORPHISM 89 And if it be said that the cases we wouldadduce are not fair samples of sex-characters,we would reply that it is very difficult todraw a line round secondary sex-charRcters,separating them from other sex-differences.This is especially difficult among invertebrateanimals where we have little knowledge ofglands of internal secretion connected with
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Fio. 17.—Female of Paper Nautilus—Argonauta argo—withits brood-ohambei shell, enveloped by the expanded eruisof two of the arms. the essential gonads, and are therefore bereftof that useful criterion of a secondary sex-character which has been discovered invertebrates. Let us consider, then, a few striking sex-differences in their bearing upon Tand-erstheory. The female paper-nautilus, or ar-gonaut, is very different from the male. Sheis much larger, she has two arms peculiarlymodified to secrete a unique shell, not homo- 90 SEX logous with other cephalopod shells, whichis used as a brood-chamber for the developingova (see Fig. 17). The small male has nosuch shell and no such modification of twoof the arms. When he is sexually mature, oneof his arms becomes laden with sperm-packetsand is discharged as a hectocotylus intothe mantle cavity of the female (see Fig. 18).These are familiar facts, but we do not

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