Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 212 CCELENTEEATA. beset with eight meridional rows of vibratile plates, which, working like oars, serve for locomotion (fig. 155). The body parenchyma in the Sponges consists principally of arno3ba-like cells, which frequently bear flagella, but which never produce stinging threads. In the Cnidaria (Polyps and Medusse), in certain cells the peculiar struc- tures known as thread cells (fig. 156 )are developed. They consist of small capsules filled with fluid, and containing a sharp-poi
Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 212 CCELENTEEATA. beset with eight meridional rows of vibratile plates, which, working like oars, serve for locomotion (fig. 155). The body parenchyma in the Sponges consists principally of arno3ba-like cells, which frequently bear flagella, but which never produce stinging threads. In the Cnidaria (Polyps and Medusse), in certain cells the peculiar struc- tures known as thread cells (fig. 156 )are developed. They consist of small capsules filled with fluid, and containing a sharp-pointed, spi- rally coiled thread; they are developed in cells which may be called cnido- blasts. Under cer- tain mechanical conditions, e. g. under influence of the pressure pro- duced by contact with a foreign body, these cap- sules burst, and the thread is sud- denly protruded, and either fastens on to the cause of disturbance or
Size: 761px × 2629px
Photo credit: © Bookworm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: archive, book, drawing, historical, history, illustration, image, page, picture, print, reference, vintage
