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A longitudinal section of an acorn, showing two cotyledons and the embryo.

Longitudinal section of an acorn

A longitudinal section of an acorn, showing two cotyledons and the embryo.

"Anona furfuracea. 1. an expanded flower; 2. a vertical section of male and female apparatus, which latter occupies the centre; 3. a vertical section of a carpel; 4. ditto of a ripe seed, showing the ruminated albumen and embryo." -Lindley, 1853

Annona

"Anona furfuracea. 1. an expanded flower; 2. a vertical section of male and female apparatus, which…

"Triglochin palustre. 1. A flower; 3. a ripe fruit; 4. one ripe carpel opened and exhibiting a seed; 5. embryo." -Lindley, 1853

Arrowgrass

"Triglochin palustre. 1. A flower; 3. a ripe fruit; 4. one ripe carpel opened and exhibiting a seed;…

"1. Spathe of Arum maculatum; 2. its spadix loaded with flowers; 3. an anther; 4. a transverse section of an ovary; 5. a cluster of ripe fruits; 6. a seed; 7. a section of the same, showing the embryo." -Lindley, 1853

Wild Arum

"1. Spathe of Arum maculatum; 2. its spadix loaded with flowers; 3. an anther; 4. a transverse section…

"Casuarina female; 2. male; 3. male flower; 4. female flower; 5. the ripe valves of the calyx, from which the fruit has been taken; 6. a section of the half ripe ovary; 7. a section of the fruit showing the seed and embryo." -Lindley, 1853

Beefwood

"Casuarina female; 2. male; 3. male flower; 4. female flower; 5. the ripe valves of the calyx, from…

"Boldoa fragrans. 1. a section of the ripe fruit; 2. the embryo shown separately." -Lindley, 1853

Boldo

"Boldoa fragrans. 1. a section of the ripe fruit; 2. the embryo shown separately." -Lindley, 1853

Transverse section of femur of a human embryo about eleven weeks old. Labels: a, rudimentary Haversian canal in cross sections; b, in longitudinal section; c, osteoblast; d, newly formed osseous substance of a lighter color; e, that of greater age; f, lacunae with their cells; g, a cell still united to an osteoblast.

Formation of Compact Bone in a Human

Transverse section of femur of a human embryo about eleven weeks old. Labels: a, rudimentary Haversian…

"Typha latifolia; 2, its fruit; 3, a section of the seed; 4, the embryo; 5, a stamen." -Lindley, 1853

Common Bulrush

"Typha latifolia; 2, its fruit; 3, a section of the seed; 4, the embryo; 5, a stamen." -Lindley, 1853

"Calathea villosa; 1. a flower cut open; 2. a transverse section of the ovary; 3. a perpendicular section of it; 4. a section of the seed of Canna; 5. a section of its embryo." -Lindley, 1853

Calathea

"Calathea villosa; 1. a flower cut open; 2. a transverse section of the ovary; 3. a perpendicular section…

An illustration of a Calystegia sepium embryo. Calystegia sepium (Larger Bindweed, Hedge Bindweed, or Rutland beauty) is a species of bindweed, with a subcosmopolitan distribution throughout temperate Northern Hemisphere in Europe, Asia, northwestern Africa, and North America, and in the temperate Southern Hemisphere in Australia, and Argentina in South America.

Calystegia Sepium Embryo

An illustration of a Calystegia sepium embryo. Calystegia sepium (Larger Bindweed, Hedge Bindweed, or…

"Gastrula of a Chalk-sponge (Olynthus). A, external view." -Whitney, 1911

Chalk Sponge Gastrula

"Gastrula of a Chalk-sponge (Olynthus). A, external view." -Whitney, 1911

"Gastrula of a Chalk-sponge (Olynthus). B, longitudinal section through the axis: g, primitive intestine; o, blastopore; i, inner cell-layer of the body-wall; e, outer cell-layer." -Whitney, 1911

Chalk Sponge Gastrula

"Gastrula of a Chalk-sponge (Olynthus). B, longitudinal section through the axis: g, primitive intestine;…

Embryo of Cherry,(Gray, 1858).

Cherry Embryo

Embryo of Cherry,(Gray, 1858).

Diagram showing vascular area in the chick. A, area pellucida; b, area vasculosa; c, area vitellina.

Vascular Area in the Chick

Diagram showing vascular area in the chick. A, area pellucida; b, area vasculosa; c, area vitellina.

"Dipterocarpus trinervis. a an anther; b a perpendicular, c a transverse, section of an ovary; d a fruit; e section of seed of Dryobalanops camphora; f its embryo unfolded." -Lindley, 1853

Dipterocarpus

"Dipterocarpus trinervis. a an anther; b a perpendicular, c a transverse, section of an ovary; d a fruit;…

Cross-section of an egg, showing the different parts.

Cross-section of an egg

Cross-section of an egg, showing the different parts.

Impregnated egg, with commencement of formation of embryo; showing the area germinativa or embryonic spot, the area pellucida, and the primitive groove or trace.

Impregnated Egg

Impregnated egg, with commencement of formation of embryo; showing the area germinativa or embryonic…

"Shark's egg laid open to show the position of the young fish" — Goodrich, 1859

Shark's egg

"Shark's egg laid open to show the position of the young fish" — Goodrich, 1859

"Ulmus campestris. 1. its flower; 2. its pistil; 3. its fruit; 4. its embryo." -Lindley, 1853

Elm

"Ulmus campestris. 1. its flower; 2. its pistil; 3. its fruit; 4. its embryo." -Lindley, 1853

Embryo of Morning Glory,(Gray, 1858).

Embryo

Embryo of Morning Glory,(Gray, 1858).

Embryo of Morning Glory,(Gray, 1858).

Embryo

Embryo of Morning Glory,(Gray, 1858).

"Portion of a similar embryo at a later stage of growth. The praegenital somite, VII PrG, is still present, but has lost its rudimentary appendages; go, the genital operculum, left half; KM, the left pecten; abp4 to abp7, the rudimentary appendages of the lung-sacs." — The Encyclopedia Britannica, 1910

Embryo

"Portion of a similar embryo at a later stage of growth. The praegenital somite, VII PrG, is still present,…

A human embryo of the fourth week. I, the chorion; 3, part of the amnion; 4, umbilical vesicle with its long pedicle passing into the abdomen; 7, the heart; 8, the liver; 9, the visceral arch destined to form the lower jaw, beneath which are two other visceral arches separated by the branchial clefts; 10, rudiment of the upper extremity, 11, that of the lower extremity; 12, the umbilical cord; 15, the eye; 16, the ear; 17, cerebral hemispheres; 18, optic lobes, corpora quadrigemina.

Embryo at Fourth Week

A human embryo of the fourth week. I, the chorion; 3, part of the amnion; 4, umbilical vesicle with…

Embryo chick (36 hours), viewed from beneath as a transparent object (magnified). Labels:pl, outline of pellucid area; FB, forebrain, or first cerebral vesicle: from its sides project op, the optic vesicles; SO, backward limit of somatopleure fold, "tucked in", under head; A, head-fold of true amnion; a', reflected layer of amnion, sometimes termed "false amnion;" sp, backward limit of splanchnopleure folds, along which run the omphalomesaraic veins uniting to form h, the heart, which is continued forwards into ba, the bulbus arteriosus; d, the foregut, lying behind the heart, and having a wide crescentic opening between the splanchnopleure folds; HB, hindbrain; MB, midbrain; pv, protovertebrae lying behind the foregut; mc, line of junction of medullary folds and of notochord; ch, front end of notochord; vpl, vertebral plated; pr, the primitive groove at its caudal end.

Embryo Chick

Embryo chick (36 hours), viewed from beneath as a transparent object (magnified). Labels:pl, outline…

Embryo chick at fourth day, viewed as a transparent object, lying on its left side. CH, cerebral hemispheres; FB, forebrain or vesicle of third ventricle, with Pn, pineal gland projecting from its summit; MB, midbrain; Cb, cerebellum; IV V, fourth ventricle; L, lens; chs, choroidal slit; Cen V, auditory vesicle; s m, superior maxillary process; 1F, 2F, 3F,4F., first, second, third, and fourth visceral folds; V, fifth nerve, sending one branch (ophthalmic) to the eye, and another to the first pharyngeal nerve, passing to the third visceral arch; G.Pg, pneumogastric nerve, passing towards the fourth visceral arch; iv, investing mass; ch, notochord; its front end cannot be seen in the living embryo, and it does not end as shown in the figure, but takes a sudden bend downwards, and then terminated in a point; Ht, heart seen through the walls of the chest; MP, muscle-plates; W, wing, showing commencing differentiation of segments, corresponding to arm, forearm, and hand; H L, hind-limb, as yet a shapeless bud, showing no differentiation. Beneath it is seen the curved tail.

Embryo Chick at Fourth Day

Embryo chick at fourth day, viewed as a transparent object, lying on its left side. CH, cerebral hemispheres;…

A transverse section through an embryo chick (26 hours). Labels: a, epiblast; b, mesoblast; c, hypoblast; d, central portion of mesoblast, which is here fused with epiblast; e, primitive groove; f, dorsal ridge.

Cells of an Embryo Chick

A transverse section through an embryo chick (26 hours). Labels: a, epiblast; b, mesoblast; c, hypoblast;…

Human embryo of fifth week with umbilical vesicle. The human umbilical vesicle never exceeds the size of a small pea.

Embryo of Fifth Week

Human embryo of fifth week with umbilical vesicle. The human umbilical vesicle never exceeds the size…

Diagram of young embryo and its vessels, showing course of circulation in the umbilical vesicle; and also that of the allantois (near the caudal extremity), which is just commencing.

Embryo Showing Course of Circulation

Diagram of young embryo and its vessels, showing course of circulation in the umbilical vesicle; and…

Diagram of embryo and its vessels, showing course of circulation. The large umbilical arteries are seen passing out in the placenta.

Embryo Showing Course of Circulation

Diagram of embryo and its vessels, showing course of circulation. The large umbilical arteries are seen…

"Figure 2 gives an outline of its form; the arrows at the side of the head show the currents of water which are seen to flow to the branchiae by the breathing of the young animal." — Goodrich. 1859

Form of the embryo

"Figure 2 gives an outline of its form; the arrows at the side of the head show the currents of water…

A, Magnified view of the head and neck of a human embryo of three weeks. Labels: 1, anterior cerebral vesicle or cerebrum; 2, middle cerebral vesicle; 3, middle or frontonasal process; 4, superior maxillary process, or first visceral arch, and below it the first cleft; 7, 8, 9, second, third, and fourth arches and clefts. B, Anterior view of the head of a human fetus of about the fifth week. 1, 2, 3, 5, the same parts as in A; 4, the external nasal or lateral frontal process: 6, the superior maxillary process; 7, the lower jaw; X, the tongue; 8, first branchial cleft becoming the meatus auditorius externus.

Head of an Embryo

A, Magnified view of the head and neck of a human embryo of three weeks. Labels: 1, anterior cerebral…

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.…

Portion of the germinal membrane, with rudiments of the embryo, from the ovum of a dog. The primitive groove, A, is not yet closed, and at its upper or cephalic end presents three dilatations, B, which correspond to the three divisions or vesicles of the brain. At its lower extremity the groove presents a lancet-shaped dilation (sinus rhomboidalis) C. The margins of the groove consist of clear pellucid nerve substance. Along the bottom of the groove is observed a faint streak, which is probably the chorda dorsalis. D. Vertebral plates.

Germinal Membrane of a Dog

Portion of the germinal membrane, with rudiments of the embryo, from the ovum of a dog. The primitive…

"Humulus Lupulus. 1. male flower; 2. female; 3. section of ovary; 4. ripe fruit; 5. section of it, showing embryo; 6. a grain of lupuline." -Lindley, 1853

Common Hop

"Humulus Lupulus. 1. male flower; 2. female; 3. section of ovary; 4. ripe fruit; 5. section of it, showing…

The embryo if an insect, <em>gryllotalpa</em>.

Insect Embryo

The embryo if an insect, gryllotalpa.

"Kielmeyera rosea. 1. the pistil; 2. a transverse section of it; 3. a ripe fruit; 4. embryo." -Lindley, 1853

Kielmeyera

"Kielmeyera rosea. 1. the pistil; 2. a transverse section of it; 3. a ripe fruit; 4. embryo." -Lindley,…

"Lardizabala triternata. 1. petals and stamens of male flower; 2. carpels; 3. fruit of a Lardizabala; 4. a cross section of it; 5. a seed; 6. a section of it, showing the embryo." -Lindley, 1853

Lardizabala

"Lardizabala triternata. 1. petals and stamens of male flower; 2. carpels; 3. fruit of a Lardizabala;…

"1. Leaf of Ouvirandra fenestralis; 2. a flower cut open; 3. section of a ripe carpel of O. Bernieriana; 4, 5. embryo in different positions: the thicker part is cotyledon, the smaller the plumule." -Lindley, 1853

Lattice Leaf Plant

"1. Leaf of Ouvirandra fenestralis; 2. a flower cut open; 3. section of a ripe carpel of O. Bernieriana;…

"Section through an early embryo of Limulus longispina, showing seven transverse divisions in the region of the unsegmented anterior carapace. The seventh, VII, is anterior to the genital operculum, op, and is the cavity of the praegenital somite which is more or less completely suppressed in subsequent development." &mdash; The Encyclopedia Britannica, 1910

Limulus Longispina

"Section through an early embryo of Limulus longispina, showing seven transverse divisions in the region…

"Mayaca vandellii; 1. a flower; 2. a cross section of its ovary; 3. a seed vessel; 4. two seeds, one of which is cut perpendicularly in order to show the embryo." -Lindley, 1853

Mayaca

"Mayaca vandellii; 1. a flower; 2. a cross section of its ovary; 3. a seed vessel; 4. two seeds, one…

"Cocculus macrocarpus. 1. male flower; 2. a petal and stamen; 3. a cluster of fruit; 4. seed; 5. section of ditto showing embryo." -Lindley, 1853

Moonseed

"Cocculus macrocarpus. 1. male flower; 2. a petal and stamen; 3. a cluster of fruit; 4. seed; 5. section…

An oat seed embryo.

Oat seed embryo

An oat seed embryo.

Osteoblasts from the parietal bone of a human embryo thirteen weeks old. Labels: a, bony septa with the cells of he lacunae; b, layers of osteoblasts; c, the latter in transition to bone corpuscles.

Osteoblasts from Embryo

Osteoblasts from the parietal bone of a human embryo thirteen weeks old. Labels: a, bony septa with…

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;…

Diagrammatic section showing the relation in a mammal between the primitive alimentary canal and the membranes of the ovum. The stage represented in this diagram corresponds to that of the fifteenth or seventeenth day in the human embryo, previous to the expansion of the allantois; c, the villous chorion; a, the amnion; a', the place of convergence of the amnion and reflexion of the false amnion a", or outer or corneous layer; e, the head and trunk of the embryo, comprising the primitive vertebrae and cerebrospinal axis; i, the simple alimentary canal in its upper and lower portions. Immediately beneath the right hand i is seen the fetal heart, lying in the anterior part of the pleuroperitoneal cavity; v, the yolk sac or umbilical vesicle; vi, the vitellointestinal opening; u, the allantois connected by a pedicle with the anal portion of the alimentary canal.

Membranes of the Ovum

Diagrammatic section showing the relation in a mammal between the primitive alimentary canal and the…

Reconstruction of peripheral nerves of human embryo of five weeks.

Peripheral Nerves of Human Embryo

Reconstruction of peripheral nerves of human embryo of five weeks.

"Pyxidanthera barbulata. 1. corolla cut open; 2. perpendicular section of the ovary; 3. anther; 4. seed; 5. embryo." -Lindley, 1853

Flowering Pixiemoss

"Pyxidanthera barbulata. 1. corolla cut open; 2. perpendicular section of the ovary; 3. anther; 4. seed;…

Diagram of an early stage of the formation of the human placenta. Labels: a, embryo; b, amnion; c, placental vessels; d, decidua reflexa; e, allantois; f, placental villi; g, mucous membrane.

Early Formation of the Placenta

Diagram of an early stage of the formation of the human placenta. Labels: a, embryo; b, amnion; c, placental…

The organ of attachment of a vertebrate embryo or fetus to the wall of the uterus or womb of the female.

Human Placenta

The organ of attachment of a vertebrate embryo or fetus to the wall of the uterus or womb of the female.

"Cycas circinalis; 1. a portion of a female frond; 2. section of the naked ovule; 3. ripe fruit; 4. embryo." -Lindley, 1853

Queen Sago

"Cycas circinalis; 1. a portion of a female frond; 2. section of the naked ovule; 3. ripe fruit; 4.…

"Smilax glycyphylla; 1. a male flower seen from above; 2. a female flower; 3. a transverse section of an ovary; 4. a seed; 5. a section of a seed, showing the embryo." -Lindley, 1853

Sweet Sarsaparilla

"Smilax glycyphylla; 1. a male flower seen from above; 2. a female flower; 3. a transverse section of…

Cross-section of a bean seed, showing the cotyledon, plumule, and caulicle.

Bean seed

Cross-section of a bean seed, showing the cotyledon, plumule, and caulicle.

"Aneilema crispatum; 1. a flower; 2. the calyx and pistil; 3. the capsule; 4, 5, seeds; 6. a section of ditto showing the embryo; 7. the papilla; 8. the embryo." -Lindley, 1853

Spiderwort

"Aneilema crispatum; 1. a flower; 2. the calyx and pistil; 3. the capsule; 4, 5, seeds; 6. a section…

Embryo of Sugar Maple,(Gray, 1858).

Sugar Maple Embryo

Embryo of Sugar Maple,(Gray, 1858).

A close up view of the head of a developing embryonic tadpole.

A developing tadpole's head

A close up view of the head of a developing embryonic tadpole.

"Batis maritima. 1. a male cone; 2. a male flower; 3. the same forced open to show the petals; 4. on of the bracteal scales; 5. a female cone; 6. a perpendicular section of the same; 7. a ripe cone; 8. a section of it; 9. a seed; 10. an embryo." -Lindley, 1853

Turtleweed

"Batis maritima. 1. a male cone; 2. a male flower; 3. the same forced open to show the petals; 4. on…

Diagrammatic view of a vertical transverse section of the uterus at the seventh week of pregnancy. Labels: c, c', cavity of uterus, which becomes the cavity of the decidua, opening at c, the cornua, into the Fallopian tubes, and at c' into the cavity of the cervix, which is closed by a plug of mucus; dv, decidua vera; dr, decidua reflexa, with the sparser villi imbedded in its substance; ds, decidua serotina, involving the more developed chorionic villi of the commencing placenta. The fetus is seen lying in the amniotic sac; passing up from the umbilicus is seen the umbilical pedicle of the yolk sac, which lies in the cavity between the amnion and chorion.

Uterus at Seventh Week of Pregnancy

Diagrammatic view of a vertical transverse section of the uterus at the seventh week of pregnancy. Labels:…

"Stratiotes aloides. 1. a flower and spathe; 2. a flower split open; 3. a fruit in its spathe; 4. a section of the fruit; 5. an embryo." -Lindley, 1853

Water Pineapple

"Stratiotes aloides. 1. a flower and spathe; 2. a flower split open; 3. a fruit in its spathe; 4. a…

"A grain of wheat. Vertical section, showing (b) the endosperm, and (a) embryo." &mdash; Encyclopedia Britannica, 1893

Wheat Grain

"A grain of wheat. Vertical section, showing (b) the endosperm, and (a) embryo." — Encyclopedia…

"A grain of wheat. Commencement of germination, showing (b) the pileola and (c) the secondary rootlets surrounded by their coleorrhizae." &mdash; Encyclopedia Britannica, 1893

Wheat Grain

"A grain of wheat. Commencement of germination, showing (b) the pileola and (c) the secondary rootlets…