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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al and social. Yet in spite of alltransfiguration, the flesh and blood attractionpersists, and we land in fallacy if we forgetthat these sex-impulses which are at oncethe glory and the shame of mankind—andthis increasingly throughout the ages—havea yet inconceivably longer history behindthem, and thence spring up within us withthe tremendous momentum of the organicpast. It is a significant fact that we are confrontedwith sex at the very roots of the genealogicaltree—in the primeval sub-kingdom of the Uni-cellulars, the Protozoa and the Protophytes.In these relatively simple organisms multi-plication takes place by fission or by budding,or by spore-formation; but along with thesemodes of multiplication there is a quitedistinct process, that combination of twoindividuals which is called conjugation. It 22 SEX used to be believed that the simplest organismsshowed no sexual reproduction, but subse-quent researches have shown that this isvery far from being the case. Many single- fit
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FlO. 3.—The Bell-Animalcule—Vortieella. A, a typicalindividual showing contractile fibre (CF) inside a non-contractile .sheath, the twisted nucleus (N), a contractilevacuole (CV), a food-vacuole (FV), the mouth, and thesurrounding cilia. B, an individual which has in partdivided into a cluster of small units or microzooids (Z).C, an individual, which may almost be called female,with which a minute individual or microzooid (M), whichmay be almost called male, is conjugating. celled organisms unite in pairs and two becomeone; ;i total conjugation in which there isobviously so far a decrease, not an increasein numbers. Others, such as many ciliatedInfusorians, show partial conjugation, that is, THE EVOLUTION OF SEX 23 they become closely united and exchangenuclear elements, after which they separateagain. In other cases, the ordinary formsproduce special elements (spores) which con-jugate, and these are sometimes dimorphic—macrospores and microspores—correspondingto the eggs and

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