The porifera and coelentera . iiovided with a similarfilament, the cnidocil, are termed cnuloblasts, and secrete in theinterior of the cell body the nematocyst, a weapon of otlence anddefence. This consists (Figs. 8*^, 9) of a vesicle, often with doublewalls, filled with fluid, the neck of which is barbed and then drawnout into a long and extremely fine tubular filament, at the tip ofwhich the tube probably opens to the exterior. When in the cell,the nematocyst has a difierent appearance ; the filament, barbs, and THE HYDROMEDUSAE neck, are formed and lie inside the vesicle, and are everted on
The porifera and coelentera . iiovided with a similarfilament, the cnidocil, are termed cnuloblasts, and secrete in theinterior of the cell body the nematocyst, a weapon of otlence anddefence. This consists (Figs. 8*^, 9) of a vesicle, often with doublewalls, filled with fluid, the neck of which is barbed and then drawnout into a long and extremely fine tubular filament, at the tip ofwhich the tube probably opens to the exterior. When in the cell,the nematocyst has a difierent appearance ; the filament, barbs, and THE HYDROMEDUSAE neck, are formed and lie inside the vesicle, and are everted only bypressure upon its walls. Two kinds of nematocyst, a larger and asmaller, are generally present, and exhibit some difterences ofdetail. Gland cells and pigment cells are not uncommon. ]\Iulti-polar ganglion cells, lying beneath the surface of the ectodermalepithelium, have been detected in numerous species. The smallerinterstitial cells, of irregular form, which fill the interspaces between ; 7. I ir. f.
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Keywords: ., bookcentury1900, bookdecade1900, booksubje, booksubjectctenophora
