Elementary text-book of zoology, general part and special part: protozoa to insecta . elementarytextbo00clau Year: 1892 ACTINOZOA. 223 principally of the ectoderm, but also of the entoderm. Each enido- hlast, from the contents of which a ncmalocyst is developed, possesses a fine superficial plasmatic process {cnidocil), which is probal:)ly veiy sensitive to mechanical stimuli, and occasions the bursting of the capsule. Very frequently the cnidoblasts are found thickly grouped to- gether at certain places, and form wart-like swellings or batteries (fig. 168). The differentiation of tissues and
Elementary text-book of zoology, general part and special part: protozoa to insecta . elementarytextbo00clau Year: 1892 ACTINOZOA. 223 principally of the ectoderm, but also of the entoderm. Each enido- hlast, from the contents of which a ncmalocyst is developed, possesses a fine superficial plasmatic process {cnidocil), which is probal:)ly veiy sensitive to mechanical stimuli, and occasions the bursting of the capsule. Very frequently the cnidoblasts are found thickly grouped to- gether at certain places, and form wart-like swellings or batteries (fig. 168). The differentiation of tissues and organs also appears to have I cached a higher stage in the Cnidaria, in comparison with the Porifera, in which cnidoblasts have not hitherto been discoveied. Sense cells, in particular, a e found in the ectoderm, and these are not seldom grouped together as specific sense organs. Nerve cells and fibres are also present; the latter often form a deeper layer of fibrous tracts beneath the superficial layer of the ec- toderm, with Fio. 168.—Group of uomatocysts at tli/j end of the tentacle of a Scyphid ma
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