Identifier: textbookofcompar01lang (find matches)
Title: Text-book of comparative anatomy
Year: 1898 (1890s)
Authors: Lang, Arnold, 1855-1914 Bernard, Henry Meyners Bernard, Matilda Haeckel, Ernst Heinrich Philipp August, 1834-1919
Subjects: Anatomy, Comparative
Publisher: London, New York, Macmillan and Co.
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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, the Amphipoda, and a few Decapoda (e.g. the Cray-fsJi), leavethe egg in a form like that of the sexually ripe animal. On the other hand inthe Isopoda, Mysictcc, and Lophogastridcc among the ScMzopoda and the Cumacea, theyoung form hatched from the egg may be very little developed, and may evenresemble a maggot-shaped Xnnplius or Metanmiplius ; but there are no early free-swimming larval forms, as the young undergo their metamorphoses in the broodpouch of the mother. The development of the parasitic Isopoda is interesting, sincehere the free-moving young or larval forms which go in search of hosts, resemble thetypical Isopoda in form and development of the body and limbs much more distinctlythan do the sexually mature animals. R B
Text Appearing After Image:
me. FIG. 269.—Moina rectirostris. Four early stages of development. A, Blastosphere, seenfrom the vegetative pole. B, Gastrula stage. C, somewhat older stage, with neural plate, closedlilastopore and sexual cells sunk below the surface; D, Nauplius stage, II, C, D, in opticallongitudinal section. In C, D, the neural plate, and in D, the rudiments of the Nauplivs limbs areprojected on to the section, ec, Ectoderm ; me, mesoderm ; g, primitive sexual cells ; en, endoJerm ;sp, neural plate; fop, blastopore; nd, nutritive yolk; m, mouth; st, stomoda?um ; aj, anterior; o-j,posterior antennae ; md, rudiments of mandible (after Grobben). B. The Arrangements of the Germ Layers and the Development of the Inner Organs may here be described by means of a few examples. I. Moina rectirostris (Order, Phyllopoda ; Sub-order, Cladocera ; Fig. 269). The segmentation of the mesolecithal egg is superficial, and somewhat unequal.In the 32 blastomere stage a blastomere lying at the vegetative pole is di

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