Читать книгу Intelligence in Plants and Animals онлайн

78 страница из 113

AGALENA AND HER FUNNEL-WEB.

House-Fly, Caught in the Toils, Becomes a Victim.

Persons unfamiliar with spiders find it difficult to distinguish the young from the old, and male from female. This is caused, in part, by the great differences between different ages and sexes of the same spider, on account of which they are supposed to belong to distinct species. The adult males and females, however, are easily distinguished from each other, and from the young, by the complete development of organs peculiar to each sex, the palpal organs on the ends of the palpi in the males, and the epigynum, a hard swollen place just in front of the opening of the ovaries in the females. Usually the males are smaller than their partners, and have, in proportion to their size, smaller abdomens and longer legs. They are generally darker colored, especially on the head and front part of the body, and markings which are distinct in the female coalesce and become darker in the male. In most species these differences are not very great, but in some, Argiope and Nephila for examples, where the males are about one-tenth as large as the females, one would hardly suppose, without other evidence, that the males and females had any relationship to each other. The palpal organs and the epigynum are sexual characters which do not attain their functional value until after the last moult has been effected.