ClipArt ETC
This diagram shows a transverse section of dero. c., caelom; c.l., cells of the so-called "lateral line"; d.m., dermo-muscular wall including muscles and skin; d.v., dorsal blood vessel; ect, ectoderm; ent, entoderm; g, gut; g.f., giant nerve fibers; gl, glandular cells assisting in digestion; m.c., circular muscle fibers; m.l., longitudinal muscle fibers; n, nephridium; n.v., ventral nerve chain, made up of nerve cells and nerve fibers; s, setae; v.v., ventral blood vessel.

Annelid

This diagram shows a transverse section of dero. c., caelom; c.l., cells of the so-called "lateral line";…

Diagram showing the Ascon type of sponge. ec., ectoderm; r.c., radiating canals; i.p., internal pores; mes., mesenchyma, e.p., external pores.

Ascon Sponge

Diagram showing the Ascon type of sponge. ec., ectoderm; r.c., radiating canals; i.p., internal pores;…

"Tangential section of a larva of Astroides calicularis which has fixed itself on a piece of cork. ec, Ectoderm; en, endoderm; mg, mesogloea; m, m, mesenteries; s, septum; b, basal plate formed of ellipsoids of carbonate of lime secreted by the basal ectoderm; ep, epitheca." — The Encyclopedia Britannica, 1910

Astroides Calicularis

"Tangential section of a larva of Astroides calicularis which has fixed itself on a piece of cork. ec,…

"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"…

"Diagram of a Diblastula. a, orifice of invagination (blastopore); b, archenteric cavity; c, endoderm; d, ectoderm." — Encyclopedia Britannica, 1893

Diblastula

"Diagram of a Diblastula. a, orifice of invagination (blastopore); b, archenteric cavity; c, endoderm;…

"Formation of the Diblastula of Eucope (one of the Calyptoblastic Hydromedusae) by delamination. A, B, C, three successive stages. ep, ectoderm; hy, endoderm; al, enteric cavity." — Encyclopedia Britannica, 1893

Diblastula

"Formation of the Diblastula of Eucope (one of the Calyptoblastic Hydromedusae) by delamination. A,…

Diagram of a longitudinal section of an embryo, showing the different areas of the blastodermic vesicle. Labels: a, pericardium; b, bucco-pharyngeal; c, ectoderm; d, entoderm; e,placental area.

Longitudinal Section of an Embryo

Diagram of a longitudinal section of an embryo, showing the different areas of the blastodermic vesicle.…

"Mosaic appearance of epithelium." — Encyclopedia Britannica, 1893

Epithelium

"Mosaic appearance of epithelium." — Encyclopedia Britannica, 1893

"Stratified epithelium." — Encyclopedia Britannica, 1893

Epithelium

"Stratified epithelium." — Encyclopedia Britannica, 1893

"A ciliated epithelium cell." — Encyclopedia Britannica, 1893

Epithelium

"A ciliated epithelium cell." — Encyclopedia Britannica, 1893

"A striated epithelium cell." — Encyclopedia Britannica, 1893

Epithelium

"A striated epithelium cell." — Encyclopedia Britannica, 1893

"A ciliated cell with one large cilium." — Encyclopedia Britannica, 1893

Epithelium

"A ciliated cell with one large cilium." — Encyclopedia Britannica, 1893

"Sense-epithelium cell of Aurelia." — Encyclopedia Britannica, 1893

Epithelium

"Sense-epithelium cell of Aurelia." — Encyclopedia Britannica, 1893

"A, Portion of the surface of a colony of Heliopora coerulea magnified, showing two calices and the surrounding coenenchymal tubes. B, Single zooid with the adjacent soft tissues as seen after removal of the skeleton by decalcification. Z1, the distal, and Z2, the proximal or intracalicular portion of the zooid; ec, ectoderm; ct, coenechymal tubes; sp, superficial network of solenia." — The Encyclopedia Britannica, 1910

Heliopora Corerulea

"A, Portion of the surface of a colony of Heliopora coerulea magnified, showing two calices and the…

"Diagram of a typical Hydrozoan polyp. EC., Ectoderm; EN., endoderm; C., the cavity of the gut (coelenteron); G., a reproducive bud; T., a tentacle; H., hypostome or oral cone; M., mouth." -Thomson, 1916

Hydrazoan Polyp

"Diagram of a typical Hydrozoan polyp. EC., Ectoderm; EN., endoderm; C., the cavity of the gut (coelenteron);…

"A, blastula in which the entoderm (ent.) is produced by proliferation from ectoderm (ect.)." -Galloway, 1915

Hydroid Blastula

"A, blastula in which the entoderm (ent.) is produced by proliferation from ectoderm (ect.)." -Galloway,…

"Diagram showing possible modifications of persons of a gymnoblastic Hydromedusa. a, hydrocaulus (stem); b, hydrohiza (root); c, enteric cavity; d, endoderm; e, ectoderm; f, perisarc (horny case); g, hydranth (hydriform person) expanded; g', hydranth (hydriform person) contracted; h, hypostome, bearing mouth at its extremity; k, sacciform gonophor (sporosac) springing from the hydrocaulus; k', sporosac springing from m, a modified hydriform person (blastostyle): the genitalia are seen surrounding the spadix or manubrium; l, medusiform person or medusa; m, blastostyle." — Encyclopedia Britannica, 1893

Hydromedusa

"Diagram showing possible modifications of persons of a gymnoblastic Hydromedusa. a, hydrocaulus (stem);…

"Diagram showing possible modifications of the persons of a Calyptoblastic Hydromedusa. a, hydrocaulus (stem); b, hydrohiza (root); c, enteric cavity; d, endoderm; e, ectoderm; f, perisarc (horny case); g, hydranth (hydriform person) expanded; h, hypostome, bearing mouth at its extremity; i, the horny cup or hydrotheca of the hydriform persons; l, medusiform person springing from n, a modified hydriform person (blastostyle); n, the norny case or gonandium enclosing the blastostyle and its buds. This and the hydrotheca i give origin to the name Calyptoblastea." — Encyclopedia Britannica, 1893

Hydromedusa

"Diagram showing possible modifications of the persons of a Calyptoblastic Hydromedusa. a, hydrocaulus…

"Modes of forming mesoderm. A and B, special mesoblasts distinguishable early in egmentation (annelid): A, surface view from active pole; B, sectional view of same. ec, micromeres destined to form ectoderm; en, macromeres destined to form entoderm; m, primitive mesoblast which produces the mesoderm. C, amaeboid mesodermal cells (c) budding from entoderm into the segmentation cavity (s.c.), in an Echinoderm. a, archenteron." — Galloway

Mesoderm

"Modes of forming mesoderm. A and B, special mesoblasts distinguishable early in egmentation (annelid):…

"Mesoderm formed by pouches from entoderm after gastrulation. A and B, early and later stages in formation of mesoderm and coelom. a, primitive gut; bp., blastopore; coe, body cavity, formed from pockets of the archenteron; ec., ectoderm; en., entoderm; m., mesoderm; m.so, body-wall mesoderm; m.sp., visceral mesoderm; s.c., segmentation cavity." -Galloway, 1915

Mesoderm Forming

"Mesoderm formed by pouches from entoderm after gastrulation. A and B, early and later stages in formation…

Diagram of a developing ovum, seen in longitudinal section. Labels: a, pericardium; b, bucco-pharyngeal; c, ectoderm; d, entoderm; e,placental area. f, spinal cord; i, brain; g, notochord; k, extra embryonic coelom; h, dorsal wall of alimentary canal.

Developing Ovum

Diagram of a developing ovum, seen in longitudinal section. Labels: a, pericardium; b, bucco-pharyngeal;…

"Diagrams of stages in the metamorphosis of Polygordius, a primitive annelid. Ectoderm throughout is represented as nucleated without cell boundaries; the entoderm has the cell-boundaries shown, and the mesoderm is diagonally shaded. A, gastrula; B, same with blastopore closed; C and D represent formation of stomodaeum and proctodaeum from ectoderm; E, Trochosphere stage showing formation of segments in the posterior portion; F, adult (sagittal); G, adult (transverse). a, archenteron; bp., blostopore; br, brain; c, coelom; d, dorsal; di, dissepiments; m, mesenteron; pr., proctodaeum; s.c., segmentation cavity; st, stomodaeum; v.n., ventral nerve chain; z, zone of formation of nerve segments." -Galloway, 1915

Polygordius

"Diagrams of stages in the metamorphosis of Polygordius, a primitive annelid. Ectoderm throughout is…

"Diagrams to illustrate the development of one of the simpler types of sponge: I, the egg; 2, section of 16- to 32-celled stage; 3, section of later stage, a ciliated larva (blastula); 4, gastrula; 5, section through older larva which has become attached by the end containing the blastopore. New openings break through by the coalescence and perforation of the ectoderm and entoderm, and and a form results... a, archenteron; bl., blastopore; ec., ectoderm; en., entoderm; mes., mesenchyma; s, segmentation cavity." -Galloway, 1915

Simple Sponge Development

"Diagrams to illustrate the development of one of the simpler types of sponge: I, the egg; 2, section…

Diagram showing the Sycon type of sponge. ec., ectoderm; r.c., radiating canals; i.p., internal pores; mes., mesenchyma, e.p., external pores; en1, entoderm; en2, flagellate entoderm; f.c., flagellate chambers.

Sycon Sponge

Diagram showing the Sycon type of sponge. ec., ectoderm; r.c., radiating canals; i.p., internal pores;…

"Sections through the unilaminar (A), bilaminar (B), and trilaminar (C) conditions of the typical biastoder. Ect., ectoderm; Ent., entoderm; Mes., mesoderm; c, primitive connective tissue." — Encyclopedia Britannica, 1893

Unilaminar

"Sections through the unilaminar (A), bilaminar (B), and trilaminar (C) conditions of the typical biastoder.…

"Diagrams illustrating two stages in the development of the vertebrate eye. A, showing the relation of the ectoderm, the brain vesicle, and the optic vesicle. The right side of the figure shows a later stage than the left. B, later stage, showing the lens, eye-ball and retina in position. b.v., brain vesicle formed by the invagination oof the ectoderm (ect.); l, lens; mes., mesodermal tissue; o.n., optic nerve; o.s., optic stalk; o.v., optic vesicle, a portion of the brain vesicle; r, retinal layer; v.h., interior of eye-ball which comes to contain the vitreous humor." — Galloway

Vertebrate Eye

"Diagrams illustrating two stages in the development of the vertebrate eye. A, showing the relation…

"Single zooid with the adjacent soft tissues as seen after removal of the exoskeleton by decalcification. Z1, the distal, and Z2, the proximal of intracalicular portion of the zooid; ec, ectoderm; ct, coenenchymal tubes; sp, superficial network of solenia." —Encyclopedia Britannica, 1910

Zooid

"Single zooid with the adjacent soft tissues as seen after removal of the exoskeleton by decalcification.…