ClipArt ETC
The human ear. Labels: A, vestibule or antechamber; B, auditory canal; C, the hammer, anvil, and the stirrup; D, semicircular canals; E, cochlea; G, Eustachian tube.

Ear

The human ear. Labels: A, vestibule or antechamber; B, auditory canal; C, the hammer, anvil, and the…

The human eye. Labels: a, crystalline lens; b, retina; c, cornea; d, sclerotic; e, choroid; g, ciliary processes; h, vitreous humor; k, pupil; i, iris; o, optic nerve.

Eye

The human eye. Labels: a, crystalline lens; b, retina; c, cornea; d, sclerotic; e, choroid; g, ciliary…

The power possessed by the hand of a human is chiefly depended upon the size and power of the thumb, which is more developed in humans than it is in the highest apes. The thumb of the human hand can be brought into exact opposition to the extremities of all the fingers, whether singly or in combination; while in those quandrumana which most nearly approach man, the thumb is so short, and the fingers are so weak that they can never be opposed to each other with any degree of force. The human foot is, in proportion to the side of the whole body, larger, broader, and stronger than that of any other mammal.

Comparison of the Hand and the Foot of a Monkey and Human

The power possessed by the hand of a human is chiefly depended upon the size and power of the thumb,…

A diagram of the human skeleton.

The Human Skeleton

A diagram of the human skeleton.

The diagram of a human ovum, showing the parts of an animal cell.

A Diagram of the Human Ovum

The diagram of a human ovum, showing the parts of an animal cell.

The diagram of a human ovum undergoing segmentation. Labels: a, human ovum; b, ovum divided into two; c, ovum divided into four; d, process has ended in the production of the so-called mulberry mass.

The Human Ovum Undergoing Segmentation

The diagram of a human ovum undergoing segmentation. Labels: a, human ovum; b, ovum divided into two;…

Ciliated epithelium from the human trachea. Large fully formed cell. Labels: b, shorter cell; c, developing cells with more than one nucleus.

Ciliated Epithelium

Ciliated epithelium from the human trachea. Large fully formed cell. Labels: b, shorter cell; c, developing…

The bone contains a multitude of small irregular spaces, approximately fusiform in shape, called lacunae, with very minute canals leading from them and anastomosing with similar little prolongations from the other lacunae. Shown is a longitudinal section from the human ulna, showing Haversian canal, lacunae, and canaliculi.

Microscopic Structure of Bone

The bone contains a multitude of small irregular spaces, approximately fusiform in shape, called lacunae,…

Bone corpuscles with their processes as seen in a thin section of human bone.

Bone Corpuscles

Bone corpuscles with their processes as seen in a thin section of human bone.

Lamellae torn off from a decalcified human parietal bone at some depth from the surface. Labels: a, lamellae, showing reticular fibers; b, darker part, where several lamellae are superposed; perforating fibers. Apertures through which perforating fibers has passed, are seen especially in the lower part of the figure.

Lamellae

Lamellae torn off from a decalcified human parietal bone at some depth from the surface. Labels: a,…

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

Osteoblasts

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

Transverse section through the tibia of a fetal kitten. Labels: P, Periosteum. O, Osteogenetic layer of periosteum showing the osteoblasts newly formed bones. B, the periosteal bone deposited in successive layers beneath the periosteum and ensheathing E, the spongy endochondral bone; represented as more deeply shaded. Within the trabeculae of endochondral spongy bone are seen the medulla, with V, veins. In the lower half of the figure the endochondral spongy bone has been completely absorbed.

Formation of Compact Bone in a Kitten

Transverse section through the tibia of a fetal kitten. Labels: P, Periosteum. O, Osteogenetic layer…

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…

Longitudinal section (A) and transverse section (B) of a human molar tooth. Labels: c, cement; d, dentine; e, enamel; v, pulp cavity

Structure of a Molar

Longitudinal section (A) and transverse section (B) of a human molar tooth. Labels: c, cement; d, dentine;…

Transverse section through muscular fibers of human tongue. The muscle corpuscles are indicated by their deeply stained nuclei situated at the inside of the sarcolemma. Each muscle fiber shows "Cohnheim's fields," that is, the sarcous elements in transverse section separated by clear (apparently linear) interstitial substance.

Muscular Fibers of the Human Tongue

Transverse section through muscular fibers of human tongue. The muscle corpuscles are indicated by their…

A. Portion of a medium sized human muscular fiber. B. Separated bundles of fibrils equally magnified. Labels: a, larger, and b, smaller collections; c, still smaller; d, smallest which could be detached, possibly representing a single series of sarcous element.

Muscular Fiber

A. Portion of a medium sized human muscular fiber. B. Separated bundles of fibrils equally magnified.…

Different forms of ganglion cells. A, a, round ball-shaped unipolar cell from the human Gasserian ganglion. Two cells only show the process f; b, spindle shaped; c, multipolar ganglion cell from he spinal cord of the ox. d, D, Purkinjee ganglion cells from human cerebellum; ax, axis cylinder process; p, protoplasmic process; h, h, two cells surrounded with a nucleated sheath.

Different Forms of Ganglion Cells

Different forms of ganglion cells. A, a, round ball-shaped unipolar cell from the human Gasserian ganglion.…

An isolated ganglion cell of a human, showing sheath with nucleated cell lining, B. A Ganglion cell, with nucleus and nucleolus. C, Branched process. D. Unbranched process.

Ganglion Cell, Structure of

An isolated ganglion cell of a human, showing sheath with nucleated cell lining, B. A Ganglion cell,…

The Pacinian bodies or corpuscles are elongated oval bodies situated on some of the cerebrospinal and sympathetic nerves, especially the cutaneous nerves of the hands and feet; and on branches of the large sympathetic plexus about the abdominal aorta. Shown are the extremities of a nerve of the finger with Pacinian corpuscles attached.

Pacinian Corpuscles in a Human

The Pacinian bodies or corpuscles are elongated oval bodies situated on some of the cerebrospinal and…

The Pacinian bodies or corpuscles are elongated oval bodies situated on some of the cerebrospinal and sympathetic nerves, especially the cutaneous nerves of the hands and feet; and on branches of the large sympathetic plexus about the abdominal aorta. Shown is the summit of a Pacinian corpuscle of a human finger, showing the endothelial membranes linking the capsules.

Pacinian Corpuscle of a Human

The Pacinian bodies or corpuscles are elongated oval bodies situated on some of the cerebrospinal and…

Touch corpuscles are found in the papillae of the skin of the fingers and toes, or among its epithelium; they may be simple or compound; when simple, they are large and slightly flattened transparent nucleated ganglion cells, enclosed in a capsule; when compound the capsule contains several smalls cells. Show is a touch corpuscle of Meissner, from the skin of the human hand.

Touch Corpuscle of Meissner

Touch corpuscles are found in the papillae of the skin of the fingers and toes, or among its epithelium;…

The clotting of the blood is due to the development in it of a substance called fibrin which appears as a meshwork of fine fibrils. Reticulum of fibrin, from a drop of human blood, after treatment rosanilin.

Reticulum of Fibrin

The clotting of the blood is due to the development in it of a substance called fibrin which appears…

Acetic acid (dilute) causes the nucleus of the red blood cells in the frog to become more clearly defined; if the action is prolonged, the nucleus becomes strongly granulated, and all the coloring matter seems to be concentrated in it, the surrounding cell substance and outline of the cell becoming almost invisible; after a time the cells lose their color altogether. The cells shown represent the successive stages of change. A similar loss of color occurs in the red cells of human blood, which , however, from the absence of nuclei, seem to disappear entirely.

Effect of Acetic Acid on Red Blood Cells

Acetic acid (dilute) causes the nucleus of the red blood cells in the frog to become more clearly defined;…

When a 2 percent fresh solution of tannic acid is applied to frog's blood it causes the appearance of a sharply defined little knob, projecting from the free surface (Robert's macula): the coloring matter becomes at the same concentrated in the nucleus, which grows more distinct. A somewhat similar effect is produced on the human blood corpuscle.

Effect of Tannin on Red Blood Cells

When a 2 percent fresh solution of tannic acid is applied to frog's blood it causes the appearance of…

Human colorless blood corpuscle, showing its successive changes of outline within ten minutes when kept moist on a warm stage.

The Change of Colorless Blood Corpuscles

Human colorless blood corpuscle, showing its successive changes of outline within ten minutes when kept…

Ciliary epithelium of the human trachea. Labels: a, layer of longitudinally arranged elastic fibers; b, basement membrane; c, deepest cells, circular in form; d, intermediate elongated cells; e, outermost layer of cells fully developed and bearing cilia.

Ciliary Epithelium

Ciliary epithelium of the human trachea. Labels: a, layer of longitudinally arranged elastic fibers;…

The capillary network of the pulmonary blood vessels in the human lung.

Capillary Network in Lung

The capillary network of the pulmonary blood vessels in the human lung.

A tonsil consists of an elevation of the mucous membrane presenting 12 to 15 orifices which lead into crypts or recesses, in the walls of which are placed nodules of adenoid or lymphoid tissue. Shown is a vertical section through a crypt of the human tonsil. Labels: 1, entrance to the crypt; 2 and 3, the framework or adenoid tissue; 4, the enclosing fibrous tissue; a and b, lymphatic follicles; 5 and 6, blood vessels.

Crypt of Tonsil

A tonsil consists of an elevation of the mucous membrane presenting 12 to 15 orifices which lead into…

A, Villus of sheep. B, Villi of human.

Villus of Humans and Sheep

A, Villus of sheep. B, Villi of human.

Sebaceous gland from the human skin.

Sebaceous Gland from Human Skin

Sebaceous gland from the human skin.

Section through the gray matter of the human cerebellum.

Gray Matter of Cerebellum

Section through the gray matter of the human cerebellum.

Brain of the Orangoutang, showing arrangement of the convolutions. Sy, fissure of Sylvius; R, fissure of Rolando; E P, external perpendicular fissure; Olf, olfactory lobe; Cb, cerebellum; PV, pons Varolii; MO, medulla oblongata. As contrasted with the human brain, the frontal lobe is short and small relatively, the fissure of Sylvius is oblique, the temporo-sphenoidal lobe very prominent, and the external perpendicular fissure very well marked.

Brain of the Orangutan

Brain of the Orangoutang, showing arrangement of the convolutions. Sy, fissure of Sylvius; R, fissure…

Nerves of the outer walls of the nasal fossae. 1, network of the branches of the olfactory nerve, descending upon the region of the superior and middle turbinated region of the superior and middle turbinated bones; 2, external twig of the ethmoidal branch of the nasal nerves; 3, spheno-palatine ganglion; 4, ramification of the anterior palatine nerves; 5, posterior, and 6, middle division of the palatine nerves; 7, branch to the region of the superior and middle turbinated bones; 9, naso-palatine branch to the septum cut short.

Nerves of the Nasal Fossae

Nerves of the outer walls of the nasal fossae. 1, network of the branches of the olfactory nerve, descending…

Interior view of the tympanum, with membrana tympani and bones in natural position. 1, Membrana tympani; 2, Eustachian tube; 3, tensor tympani muscle; 4, lig. mallei super; 6, corda-tympani nerve; a, b, and c, sinuses about ossicula.

Tympanum

Interior view of the tympanum, with membrana tympani and bones in natural position. 1, Membrana tympani;…

Section through the choroid coat of the human eye. Labels: 1, elastic membrane, structureless or finely fibrillated; 2, chorio-capillaris or tunica Ruyschiana; 3, Proper substance of the choroid with large vessels cut through; 4, suprachoroidea; 5, sclerotic.

Section Through the Choroid Coat

Section through the choroid coat of the human eye. Labels: 1, elastic membrane, structureless or finely…

Section through the macula lutea and fovea centralis of the human retina. Labels: a, fovea; b, descent of the macula towards fovea. The numbers indicate the layers of the retina: 1, membrana limitans interna; 2, optic nerve fibers; 3, layer of ganglionic corpuscles; 4, inner molecular layer; 5, inner nuclear layer; 6, intergranular, internuclear, or outer molecular layer. 7, external nuclear layer; 8, membrana limitans externa; 9, layer of rods and cones; 10, pigment-cell layer.

Layers of the Retina

Section through the macula lutea and fovea centralis of the human retina. Labels: a, fovea; b, descent…

Spermatozoa of the salamander (1) and human (2). Labels: a, long pointed head; b, elliptical structure ; c, filiform body; d, fine filament; e, homogeneous membrane.

Spermatozoa of a Salamander and Human

Spermatozoa of the salamander (1) and human (2). Labels: a, long pointed head; b, elliptical structure…

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…

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…

Very soon after the entrance of the ovum into the uterus, in the human subject, the outer surface of the chorion is found beset with fine processes, the so-called chorion villi, which give it a rough and shaggy appearance. a, chorion with villi. The villi are shown to be best developed in the part of the chorion to which the allantois is extending, this portion ultimately becomes the placenta. ; b, space between the two layers of the amnion; c, amniotic cavity; d, situation of the intestine, showing its connection with the umbilical vesicle; e, umbilical vesicle; f, situation of heart and vessels; g, allantois.

Chorion Villi

Very soon after the entrance of the ovum into the uterus, in the human subject, the outer surface of…

Very soon after the entrance of the ovum into the uterus, in the human subject, the outer surface of the chorion is found beset with fine processes, the so-called chorion villi, which give it a rough and shaggy appearance. Shown is a magnified view of chorion villi.

Magnified View of Chorion Villi

Very soon after the entrance of the ovum into the uterus, in the human subject, the outer surface of…

Section of the lining membrane of a human uterus at the period of commencing pregnancy showing the arrangement and other peculiarities of the glands, d, with their orfices, a, on the internal surface of the organ.

Lining Membrane of the Uterus

Section of the lining membrane of a human uterus at the period of commencing pregnancy showing the arrangement…

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…

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…

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…

Early stages in development of human brain. 1, 2, 3, are from an embryo about seven weeks old; 4, about three months old. m, middle cerebral vesicle (mesencephalon); c, cerebellum; m o, medulla oblongata; i, thalamencephalon; h, hemispheres; i', infundibulum; Fig. 3 shows the several curves which occur in the course of development; Fig. 4 is a lateral view, showing the great enlargement of the cerebral hemispheres which have covered in the thalami, leaving the optic lobes, m, uncovered.

Development of the Brain

Early stages in development of human brain. 1, 2, 3, are from an embryo about seven weeks old; 4, about…

Diagrammatic sketch of a vertical longitudinal section through the eyeball of a human fetus of four weeks. The section is a little to the side, so as to avoid passing through the ocular cleft; c, the cuticle where it becomes later the corneal epithelium; l, the lens; op, optic nerve formed by the pedicle of the primary optic vesicle; vp, primary medullary cavity or optic vesicle; p, the pigment layer of the retina; r, the inner wall forming the retina proper; vs, secondary optic vesicle containing the rudiment of the vitreous humour.

Eye of Fetus of Four Weeks

Diagrammatic sketch of a vertical longitudinal section through the eyeball of a human fetus of four…

Transverse vertical section of the eyeball of a human embryo of four weeks. The anterior half of the section is represented: pr, the remains of the cavity of the primary optic vesicle; p, the inner part of the outer layer forming the retinal pigment; r, the thickened inner part giving rise to the columnar and other structures of the retina; v, the commencing vitreous humour within the secondary optic vesicle; v', the ocular cleft through which the loop of the central blood vessel, a, projects from below; l, the lends with a central cavity.

Eye of Fetus of Four Weeks

Transverse vertical section of the eyeball of a human embryo of four weeks. The anterior half of the…

Illustrating the relationship of the lateral incisor tooth to the palatal cleft. A, Normal hard palate. The premaxilla is stippled; the lateral incisor occurs in the suture between it and the maxilla. B, Double cleft palate, the lateral incisor being situated on the premaxilla to the inner side of the cleft. The septum of the nose is exposed in the cleft between the maxillary bones. C, Double cleft palate, the lateral incisor being situated on the maxilla to the outer side of the cleft.

Incisor Relation to Palatal Cleft

Illustrating the relationship of the lateral incisor tooth to the palatal cleft. A, Normal hard palate.…

"Ruby-eyed Limpet, from the Antilles. If the common Limpet is alarmed, no human force, pulling in a direct line, can remove it."

Patella Granatina (Linnaeus)

"Ruby-eyed Limpet, from the Antilles. If the common Limpet is alarmed, no human force, pulling in a…

Oblique anteroposterior section of foot, to show the synovial cavities of the tarsus. Labels: 1, tibia; 2, fibula; 3, astragalus; 4, os calcis; 5, external lateral ligament; 6, internal lateral ligament; 7, interosseous ligament between astragalus and os calcis; 8, head of astragalus; 9, scaphoid; 10, 11, and 12, the three cuneiform bones; 13, cuboid.

Oblique Anteroposterior Section of

Oblique anteroposterior section of foot, to show the synovial cavities of the tarsus. Labels: 1, tibia;…

Lifrac's operation consists in amputation through the tarsometatarsal line of joints. Labels: a, b, c, inner, middle and outer cuneiform bones; d, cuboid; e, f, the metatarsal bones; g, tibialis anticus; h, extensor proprius hallucis; i, extensor communis digitorum; j, extensor brevis digitorum; k, extensor tendons; l, dorsalis pedis artery.

Lisfranc's Amputation at the Tarsometatarsal Joint

Lifrac's operation consists in amputation through the tarsometatarsal line of joints. Labels: a, b,…

"Section through right ear. 1, helix; 2, concha; 3, outer passage; 4, 5, 6, semi-circular canals; 7, oval window; 8, cochlea; 9, Eustachian tube; 10, eardrum." -Foster, 1921

Ear

"Section through right ear. 1, helix; 2, concha; 3, outer passage; 4, 5, 6, semi-circular canals; 7,…

"Section through the left eye, closed. 1, lifting muscle; 2, upper straight muscle; 3, optic nerve; 4, fatty cushion; 5, lower straight muscle; 6, vitreous humor; 7, lower cross muscle; 8, lower eyelid; 9, upper eyelid; 10, crystalline lens." -Foster, 1921

Eye Section

"Section through the left eye, closed. 1, lifting muscle; 2, upper straight muscle; 3, optic nerve;…

"Cross-section of the eye. Parts: co, cornea; I, iris; aq, anterior chamber of aqueous humor; L, lens; cp, ciliary process; sc, sclerotic coat; R, retina; ch, choroid; V, vitreous body; m, yellow spot; bs, blind spot; O, optic nerve." -Foster, 1921

Eye Cross-Section

"Cross-section of the eye. Parts: co, cornea; I, iris; aq, anterior chamber of aqueous humor; L, lens;…

"The foot. a, calcaneum; b, astragalus; c, cuboid; d, metatarsal, of which there are five; e, phalanges, of which there are five; f, external cuneiform; g, middle cuneiform; h, scaphoid." -Foster, 1921

Foot Bones

"The foot. a, calcaneum; b, astragalus; c, cuboid; d, metatarsal, of which there are five; e, phalanges,…

"The skull in reptiles is flat, and the cerebral cavity is not filled with brains. There are no ribs."

Skeleton of a Frog

"The skull in reptiles is flat, and the cerebral cavity is not filled with brains. There are no ribs."

"The external air penetrates into every part of their body by the respiratory tubes, which ramify the whole cellular tissue. Wings alone would fail to support the bird."

Skeleton of the Swan

"The external air penetrates into every part of their body by the respiratory tubes, which ramify the…

The trunk showing rib, iliac crest, and pubis.

Side View of the Bones of the Trunk

The trunk showing rib, iliac crest, and pubis.

Back view of the trunk.

Back View of the Bones of the Trunk

Back view of the trunk.