"Portion of the body-wall of Hydra, showing ectoderm cells above, separated by "structureless lamelia" from three flagellate endoderm cells below. The latter are vacnolated, and contain each a nucleus and several dark granules. In the middle ectoderm cell are seen a nucleus and three nematocysts, with trigger hairs projecting beyond the cuticle. A large nematocyst with everted thread, is seen in the right-hand ectodermal cell." — Encyclopedia Britannica, 1893

Body-wall

"Portion of the body-wall of Hydra, showing ectoderm cells above, separated by "structureless lamelia"…