Introduction to zoology; a guide to the study of animals, for the use of secondary schools; Year: 1900 (1900s) Authors: Davenport, Charles Benedict, 1866-1944 Davenport, Gertrude Anna Crotty, 1866- Subjects: Zoology Publisher: New York, Macmillan company

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Genus Nais Identifier: introductiontozo00dave Title: Introduction to zoology; a guide to the study of animals, for the use of secondary schools; Year: 1900 (1900s) Authors: Davenport, Charles Benedict, 1866-1944 Davenport, Gertrude Anna Crotty, 1866- Subjects: Zoology Publisher: New York, Macmillan company London, Macmillian and co., ltd. Contributing Library: MBLWHOI Library Digitizing Sponsor: MBLWHOI Library
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Text Appearing Before Image: e bodytransversely. In themiddle of the bodytentacles begin toarise, a new mouth isformed, and the wormconstricts into two.I n d e e d, sometimesseveral new heads maybe forming in themidst of a singleworm. This habit isof advantage not onlyin multiplying thenumber of individualsof the species, but also as a means of protection. For if, by chance, the larva of the water-beetle Dytiscus seizes a Nais and bites it in two, the part which escapes can go on developing new^ individuals.The slow-moving, burrowing habit of the earthworm has led to a nearly complete absence of such appendages as Nereis possesses. There are other ringed worms i • T , i i . i -i •, FIG. 125. — Phasci)- in which the burrowing habits have led to iosoma, a Gephy- a loss even of the segments in the adult. rean- One-fourth r™ • • , i ,-, ,. nat. size. From 11 us is the case in the group Gephyrea.1 Leunis. 1 ytfivpa, bridge ; because they were once considered to bridge the gapbetween holothurians and worms. Text Appearing After Image: FIG. 124. — Nais: a, mouth; b, anus; c, intes-tine. From Leunis.
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