File:Heredity and sex (1913) (14778399764).jpg

Identifier: hereditysex1913morg (find matches)
Title: Heredity and sex
Year: 1913 (1910s)
Authors: Morgan, Thomas Hunt, 1866-1945
Subjects: Heredity Sex Heredity
Publisher: New York, Columbia University Press
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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re parasitized by another crustacean, sacculina (acirriped or barnacle), they develop the secondary sexualcharacters of the female. Geoffrey Smith has confirmedthese results and carried them further in certain re-spects. Smith finds that the spider crab, Inachusmauritanicus, is frequently infected by Sacculina neglecta(Fig. 79). The parasite attaches itself to the crab andsends root-like outgrowths into its future host. Theseroots grow like a tumor, and send ramifications to allparts of the body of the crab. The chief effect of the parasite is to cause completeor partial atrophy of the reproductive organs of thecrab, and also to change the secondary sexual charac-ters. Smith says that of 1000 crabs infected by 156 HEREDITY AND SEX sacculina, 70% of both males and females showedalterations in their secondary sexual characters. As a control, 5000 individuals not infected were ex-amined, only one was unusual, and this one was a her-maphrodite (or else a crab recovered from its parasite).
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Fig. 79. — A male of Inachus mauritanicus (upper left hand). Female ofInachus scorpi (lower left hand). Male of Inachus mauritanicus carrying onits abdomen two specimens of Danalia curvata and a small Sacculina neglecta(upper right hand). Male of Inachus mauritanicus with a Sacculina neglectaon it (lower right hand). The abdomen and chelae of the host are inter-mediate in character between those of an ordinary male and female. (AfterGeoffrey Smith.) As the figures (Fig. 80) show, the adult male haslarge claws; the female, small ones. He has a narrowabdomen; she has a broad one. In the male thereis a pair of stylets on the first abdominal ring (anda pair of greatly reduced appendages behind them).The adult female has four biramous abdominal append-ages with hairs to carry the eggs. THE EFFECTS OF CASTRATION 157

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