General principles of zoology . - &•—Cyclops (A) and also the nauplius in lateral (.5) and in ventral view (C).1-v , the five thoracic, and behind these the five abdominal segments ; F, furca ; i, thenrst, 2, the second, antennae; 3, mandibles ; 4. maxilla;; 5, pedes maxillares (maxillipeds);6-9, the first four pairs of biramous feet, while the rudimentary fifth pair are hidden ;•a«, eye ; a, upper lip ; e, egg-sacs ; </, gut ; m, muscle. GENERAL PRINCIPLES OF ZOOLOGY. appearance it belongs to the surface of the body, becausethis mediates the relations with the external world, th
General principles of zoology . - &•—Cyclops (A) and also the nauplius in lateral (.5) and in ventral view (C).1-v , the five thoracic, and behind these the five abdominal segments ; F, furca ; i, thenrst, 2, the second, antennae; 3, mandibles ; 4. maxilla;; 5, pedes maxillares (maxillipeds);6-9, the first four pairs of biramous feet, while the rudimentary fifth pair are hidden ;•a«, eye ; a, upper lip ; e, egg-sacs ; </, gut ; m, muscle. GENERAL PRINCIPLES OF ZOOLOGY. appearance it belongs to the surface of the body, becausethis mediates the relations with the external world, theregulation of which relations is subserved by the central mf mf - mp 1. ~ep III. FlG. o.—Cross-sections throughthe Dorsal Regions of Triton embryos at three different (From O. Hertwig.) I. The Medullary Plate (rudiment of the spinal cord), nip. is;marked off from the skin, n/>. medullaryplate ; n, the medullary or neural tube (spinal cord) arising from it ; <?/, skin (epider-mis) ; c/i, notochord ; »ik, middle germ-layer ; ttnA-1, its parietal, mk*, its visceral layer);c, coelom (body-cavity); cf, cavity of a primitive segment or mesoblastic somite ; ik,.inner germ-layer ; dz, its yolk-cells ; Ig, lumen of the gut. nervous system. In the case of higher organized animals, the vertebrates, the brain and spinal cord lie deeplyembedded in the interior of the body; but in the embryo* HISTORY OF ZOOLOGY. 47 it is laid dow
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1896
