. A manual of elementary zoology . Zoology. 26 MANUAL OF ELEMENTARY ZOOLOGY of toads and newts. The pigment in the cells expands and contracts in varying conditions of light and temperature and thus alters the colour of the frog. Cold, dark, or kwet surroundings cause expansion of the pigment and darkening of the skin. Warmth, light, or dryness cause contraction (PI. III.). From time to time the horny outer layer of the skin is shed and eaten by the frog. Immediately below the skin is a series of large spaces, General the subcutaneous lymph sacs, containing a fluid of Interna?Bt known as lymph
. A manual of elementary zoology . Zoology. 26 MANUAL OF ELEMENTARY ZOOLOGY of toads and newts. The pigment in the cells expands and contracts in varying conditions of light and temperature and thus alters the colour of the frog. Cold, dark, or kwet surroundings cause expansion of the pigment and darkening of the skin. Warmth, light, or dryness cause contraction (PI. III.). From time to time the horny outer layer of the skin is shed and eaten by the frog. Immediately below the skin is a series of large spaces, General the subcutaneous lymph sacs, containing a fluid of Interna?Bt known as lymph (p. 60). Between the lymph sacs organs. the skin is bound down to the underlying flesh by tough, white connective tissue, but in consequence of the presence of the sacs it is much looser than that of most animals. Below the sacs the body possesses a continuous layer of .-. flesh, which con- sists, as the sub- stance so-called always does, of muscles. There is FIG. 9.—A diagram of a transverse section thuS a , hody-wall through the abdomen of a male frog. composed Ot skin and muscles, with bones coe., Ccelom; d. ao., dorsal aorta ; , dorsal lymph j ... r sac ; , dorsal subcutaneous lymph sac; g-., and a lining Ot peri- gut; z>.c, inferior vena cava ;£., kidney; !., toneum (tO be men- lateral subcutaneous lymph sac; msnt., mesen- . j u l \ j tery; mso., mesorchium ; muse, muscular body- tlOned Shortly), and wall; »., spinal nerves; J>er., peritoneum; si., ..l: 11 ;n skin; , spinal cord; <., testis; v., vertebra; tms waU encloses in , ventral subcutaneous lymph sac. the trunk a large space, the body cavity or ccelom, in which lie most of the principal viscera. The latter name is applied to the soft internal organs of the body, such as the stomach, bowels, liver, lungs, and heart. The body-wall of the back is much thicker than that of the belly, and in it is embedded a structure known as the backbone, spine, or vertebral column. This
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectzoology, bookyear1920
