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"Life history of a coral, Monoxenia darwinii. A, B, Ovum. C, Division into two. D, four-cell stage. E, Blastula. F, Free-swimming blastula with cilia. G, Section of blastula. H, Beginning of invagination. I, Section of completed gastrula, showing ectoderm, and archenteron. K, Free-swimming ciliiated gastrula." -Thomson, 1916

Coral Stages

"Life history of a coral, Monoxenia darwinii. A, B, Ovum. C, Division into two. D, four-cell stage.…

"Further development of hen's egg; after Haeckel: A, the mulberry mass of cleavage cells, b, same as seen on top in fig 111, F, here viewed in profile in section, resting upon n, the simply-shaded part of the figure, to represent conventionally the mass of food-yelk. A, morula stage (as before); B, blastula stage, the mass of cells, b, forming the blastoderm, uplifted from the food-yelk, leaving the cleavage-cavity, s; w, the thickened rim of the germ-disc; C, the blastula in process of inversion, by which a layer of entoderm-cells, i, growing from periphery to centre, will apply itself to the layer of exoderm-cells, e, obliterating the cleavage-cavity, s; D, the disc-gastrula completed, by union of entoderm, i, with exoderm, e, leaving the primitive intestinal cavity, d, which is quite similar in appearance to the cleavage cavity, s, but morphologically quite different." Elliot Coues, 1884

Egg Germination

"Further development of hen's egg; after Haeckel: A, the mulberry mass of cleavage cells, b, same as…

"Early stages in the development of Amphioxus. 1. Ovum with germinal vesicle; 2. four-cell stage; 3. external appearance of blastula; 4. blastula in section; 5. beginning of gastrula stage; 6. section of completed gastrula." -Thomson, 1916

Lancelet Stages

"Early stages in the development of Amphioxus. 1. Ovum with germinal vesicle; 2. four-cell stage; 3.…

"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…

The sponge, a many celled animal, begins its life as a single-cell, the egg. The continued division of its cells result in the formation of a hollow globe of cells called the blastula, similar to Volvox, and at this point the young larva leaves the parent.

Sponge Develoment

The sponge, a many celled animal, begins its life as a single-cell, the egg. The continued division…

The sponge, a many celled animal, that begins its life as a single-cell, the egg. The continued division of its cells result in the formation of a hollow globe of cells called the blastula, similar to Volvox, and at this point the young larva leaves the parent.

Sponge Develoment

The sponge, a many celled animal, that begins its life as a single-cell, the egg. The continued division…

The sponge, a many celled animal, begins its life as a single-cell, the egg. After division of cells and formation of blastula, the young larva leaves the parent. The next transformation consists of a pushing in of one side. This depression deepens and gradually results in the formation of a two layered sac know as the gastrula.

Sponge Develoment

The sponge, a many celled animal, begins its life as a single-cell, the egg. After division of cells…