Entomology : with special reference to its biological and economic aspects . butterfly, Papilio. rather irregular. A scale is the equivalent of a hair, for (i) a complete seriesof transitions from hairs to scales may be found on a singleindividual (Fig. 95) ;? and (2) hairs and scales agree in theirmanner of development, as shown by Semper, Schaffer, Spu- FiG. Hairs and scales of a moth, Samia cecropia. ler, Mayer and others. Both hairs and scales arise as pro-cesses from enlarged hypodermis cells, or formative cells (). The scale at first contains protoplasm, which graduallywithdra
Entomology : with special reference to its biological and economic aspects . butterfly, Papilio. rather irregular. A scale is the equivalent of a hair, for (i) a complete seriesof transitions from hairs to scales may be found on a singleindividual (Fig. 95) ;? and (2) hairs and scales agree in theirmanner of development, as shown by Semper, Schaffer, Spu- FiG. Hairs and scales of a moth, Samia cecropia. ler, Mayer and others. Both hairs and scales arise as pro-cesses from enlarged hypodermis cells, or formative cells (). The scale at first contains protoplasm, which graduallywithdraws, leaving short chitinous strands to hold the twomembranes of the scale together. ANATOMY AND PHYSIOLOGY 79 Uses of Scales.—Among Tliysannra and CoUenibola, scalesoccur only on such species as live in comparatively drv situa-tions, from which it may be inferred that the scales serve toretard the evaporation of moisture through the delicate integu-ment of these insects. This inference is supported by the fact Fig. 96.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectentomology, bookyear1
