How To Study Living Animals

Review Questions and Library Exercise

1. Show how the sexual method of reproduction tends to produce variations.

2. What is meant by the term heredity?

3. What are chromosomes? What do some zoölogists believe to be the relation between these chromosomes and heredity?

4. What are dominant and recessive characters? What is meant by “Mendel law of heredity”?

5. What is meant by the term parthenogenesis? What are some of its advantages and under what conditions does it take place? Name some animal in which parthenogenesis commonly takes place.

6. What is sex dimorphism? Give some examples.

7. What were the experiments of Professor Loeb and others in connection with artificially fertilized eggs?

8. How do eggs vary as to the kind of shell, amount of food, size, etc.? What is the effect of the amount of food upon the rate of development? On the stage of development at which the egg is hatched?

9. Contrast præcocial and altricial birds.

10. What is the effect of ground nesting and tree nesting upon the number of eggs and the care of the young?

11. Describe the metamorphosis of grasshopper, June beetle, honeybee, dragon-fly, cicada, may-fly, ant-lion, caddis fly.

12. Compare the development of the crayfish, crab, and lobster. What names are given to the larvæ? What is the significance in the fact that the lobster hatches in the “mysis stage”?

13. What are some of the peculiar names given to the larvæ in the case of echinoderms, worms, and mollusks? Why should these have received special names?

14. Name the three primitive germ layers. State the principal organs derived from each in the higher animals.

15. What is ontogeny? phylogeny? What is the meaning of the law “The ontogeny is an epitome of the phylogeny”?

16. Who was Weissman? What important contribution did he make to zoölogy?

17. With what phase of zoölogy is the name of T. H. Morgan associated?



Either pictures or specimens of the different breeds of fowl.

General Information.

Under the term poultry are included chickens as well as turkeys, pigeons, ducks, geese, etc. Chickens are most generally raised, since they do not require such special conditions as the others. In this exercise only this form of poultry is considered.

The hen has been domesticated from prehistoric times, being probably derived from the so-called jungle fowl of India (Gallus bankiva), which is still to be found in its native habitat. Through constant attempts to improve the domestic fowl along the lines of greater egg-production, size, etc., there have been developed a great many different breeds of fowl. These may be divided into seven groups, as follows:

1. The American Class.

2. The Asiatic Class.

3. The Mediterranean Class.

4. The English Class.

5. The Dutch Class.

6. The French Class.

7. The Ornamental and Exhibition Classes.

The American Class includes fowls raised both for egg-production and for eating herunterladen. It includes the following well-known breeds: the Plymouth Rocks, the Wyandottes, the Rhode Island Reds, and the less-known breeds of Javas, Dominiques, and Jersey Blues. These all lay good-sized brown eggs, are good winter layers, and stand confinement well. The standard weight varies from six and one half pounds to seven and one half pounds for the hen, and from eight and one half pounds to nine and one half pounds for the cock, the Plymouth Rocks being the heaviest of the breeds.

There are three principal varieties of Plymouth Rocks—the Barred Rocks, with grayish-white plumage regularly crossed with bars of blue-black, the White Rocks, and the Buff Rocks. All have single upright combs, which, with the wattles and the ear lobes, are bright red, a large bright eye, and yellow legs.

There are also three principal varieties of Wyandottes. The Silver-laced Wyandotte has a silvery-white plumage, with black markings in various parts of the body. The Golden Wyandotte is similar in its markings, but has yellow where the Silver-laced has white. The White Wyandotte is pure white. All have rose combs, red ear lobes, and yellow legs. They are on the average about a pound lighter than the Plymouth Rocks.

The Rhode Island Reds are a much more recent breed that has of late become very popular. They are of a reddish-brown color, about the weight of the Wyandotte, with yellow legs. There are both single combed and rose combed varieties.

The Asiatic Class includes those breeds raised chiefly for the table. The Brahmas, Cochins, and Langshans are the chief breeds. They are considerably heavier than other breeds, and are specially characterized by the feathers on the legs and feet. They all lay brown eggs, and are in many cases good layers.

The Brahmas include two principal varieties, the light and the dark. The general color is black and white, and they have yellow legs, red wattles, ear lobes, and comb, the latter being of the kind called a pea-comb, which is of small size in the cock.

There are four varieties of Cochins, the Buff being much more raised than the Partridge, the White, or the Black. The Partridge somewhat resembles a dark Brahma, but has red and brown plumage. Cochins have single combs, yellow legs, and a general fluffy character to the plumage, that of saddle and hackle meeting, thus giving a characteristic appearance to these fowls. The eggs are not quite so large as the other two breeds of this class.

The Langshans are smaller and more active than the two breeds just described. They have black legs, the feet are not so heavily feathered, and in general these fowls are much less awkward in appearance. There are two varieties, the White and the Black.

The Mediterranean Class includes those breeds raised chiefly because of their great egg-production. They are active birds, often troublesome because of their ability to fly over high enclosures, so that when kept in the city it is usually necessary to clip one wing. They are not so good winter layers as a rule, but are non-setters. They all lay white eggs. The chief breeds included are the Leghorns, the Minorcas, and the Black Spanish.

The Leghorns—the most popular of these breeds—include two chief varieties, the Brown and the White. The comb is most commonly single, falling to one side in the hen, the wattles long and pendulous, the ear lobes white, and the legs yellow.

The Minorcas are glossy black in color, with a large drooping comb in the hen, and long, thin, pendulous wattle. They lay a very large egg.

The Black Spanish resemble the Minorcas, but are distinguished by the white face and cheeks and the white on the inner edge of the wattles herunterladen.

The English Class includes the Orpingtons and the Dorkings. The Dorkings are one of the oldest breeds of fowl, and sufficiently identified by the presence of a fifth toe. There are three varieties—the White, the Silver-gray, and the Colored. The White Dorking has a rose comb; the Silver-gray has a single comb and silvery-gray plumage with black markings, the hen having a salmon-colored breast; the Colored Dorkings have sometimes single and sometimes rose combs, the plumage of the cock being black and straw-colored and that of the hen being black and gray with the breast salmon marked with black.

The Orpingtons are short legged, with close plumage. They are of large size, the hens being from seven to eight pounds and the cocks from nine to ten pounds. There are three varieties—the black, the buff, and the white. The black, except for shape, might be mistaken for a Minorca, but has red ear lobes and black shanks. The Orpingtons have the reputation of maturing early, some strains being known to lay when four months old.

The Dutch Class includes the Red-caps, the Campines, and the various varieties of the Hamburgs—of which there are six: the Golden Spangled, the Silver Spangled, the Golden Penciled, the Silver Penciled, the Black and the White. They are all good layers and non-setters, “but lay a small egg, white in color. They are readily recognized by their peculiar rose comb with its long, spikelike projection in the back, their red face, white ear lobes, and bluish legs. The prevailing color of the golden varieties is a reddish bay marked with black and of the silver varieties white marked with black. The cock usually has more dark markings than the hen.

The Red-caps are large fowl with a red and black plumage. The comb is similar to the Hamburg’s but larger, and the ear lobes are red.

The Campines resemble the Hamburgs, but have a single comb.

The French Class includes the Houdans, the Crevecœurs, and the La Fleche. The Houdans are mottled black and white with pinkish white legs, with a fifth toe like the Dorkings, and are easily recognized by their peculiar crest.

The other breeds of fowl, like the crested Polish, Bantams, and game fowl, have less interest for the poultry raiser, though often seen in exhibitions and poultry shows.

To sum up, we may group all these breeds according to their value into (1) the egg breeds, including the Leghorn, Minorca, Spanish, and Red-cap; (2) the meat breeds, including the Brahmas, Cochins, and Langshans; (3) the general purpose breeds, including the Plymouth Rocks, Wyandottes, Rhode Island Reds, Dorkings, and Orpingtons; and (4) the fancy breeds, including the Polish, Bantams, Games, etc.


American Standard of Perfection, an illustrated volume published by the American Poultry Association, indicating the desirable points of each recognized breed of fowl.


the fleshy outgrowth on the head.

Single comb,

a thin, upright comb.

Rose comb,

a flat comb with a rough or corrugated surface.

Pea comb,

resembling three single combs, united at the back.


the fleshy outgrowths from the underside of the throat.

Ear lobes,

the fleshy structure in the region of the ear.


the color noted when the coverts are raised.


the feathers on the neck.


the feathers back of the hackle.


the feathers in the posterior region of the back.


the curved feathers of the tail in the cock.


small stripes or color markings on the feather.


large spots or splotches of color on the feather.


the exposed scaly portions of the legs, usually spoken of as the “legs.”

Questions and observations microsoft office kostenlos downloaden vollversion deutsch chip.

1. Make a diagrammatic sketch of a fowl and locate the principal regions used in the description of the various breeds.

2. Observing the specimens or the pictures of the fowls at hand, note the size and kind of comb, the appearance of the wattles, the color of the eyes and ear lobes, the color in the various regions of the body, the color and any peculiarity of the legs and feet. If you wish, you may record your answers in tabular form.

Topics for investigation.

1. Look up and report upon the average number of eggs laid annually, and the number of eggs to the pound, in the case of the Plymouth Rock, Wyandotte, Rhode Island Red, Dorking, Brahma, Leghorn, and Minorca.

2. Explain the terms “non-setter” and “winter layer.”

3. When do hens moult? How does this affect the laying? What schemes have poultry men to bring this moulting at the most favorable season?

4. What is a “balanced ration” as applied to fowls? What are some methods of feeding which tend to secure greater egg-production?

5. Explain some of the special features of such methods of housing and keeping chickens as the Philo System, Corning System, etc.

6. What precautions must be taken in raising chickens so as to prevent disease and attacks of enemies?

7. What does it cost per year to keep a dozen hens? How many can a person keep profitably on a city lot, if he is not to make a special business of chicken raising?

8. How do chickens solve the problem of the garbage can?

9. What are some of the objections made to keeping chickens in the city? Are these objections well founded, and if so how may they be met?

10. Find out what breeds of chickens are kept in your neighborhood, and note some of the reasons that are given for keeping these particular breeds.


Ab do’ men, (1) the hinder portion of the body of an invertebrate; (2) of higher animals, the region or cavity containing the stomach, intestine, etc.

Al bu’ men, (1) a proteid substance; (2) “white of egg.”

A’ nal, pertaining to the anus, or hinder opening of the intestine.

Anal fin, a ventral median fin of fishes, just back of the anus.

Animal Communities, associations of many animals of the same species.

An ten’ na, a segmented sensory appendage on the head of an arthropod.

An ten’ nule, a small antenna.

An te’ ri or, farther forward, in front of; at the head or forward end.

A or’ ta, a large artery arising at the heart and forming the trunk of the arterial system.

Ap’ er ture, an opening.

Ap pend’ age, a projection from the body, usually one of a pair.

Ar throp’ o da, a group of animals with a segmented trunk and paired, segmented appendages.

Ar ti o dac’ tyl, an ungulate with an even number of toes.

A sex’ u al, without sex.

Au’ di to ry, pertaining to hearing.

Barb, one of the lateral outgrowths of the shaft of a feather, forming the vane.

Barb ule, a small outgrowth of the barb of a feather.

Bi lat’ er al sym’ me try, having the right and left sides mirror images one of the other.

Body cavity, the space between the body wall and the alimentary canal.

Body-wall, the outer wall in bodies of the many-celled animals.

Budding, a form of fission in which a cell or portion of the body forms a small protuberance or bud, which is then cut off from the parent and forms a new individual.

Canals, channels through the body-walls of sponges.

Car’ a pace, the shell which covers a portion or all of the cephalo-thorax in crustaceans.

Car’ di nal, pertaining to a cardo or hinge.

Car niv’ or ous, flesh-eating.

Car ot’ id, a large artery which supplies the brain and head with blood.

Car’ pal, a bone of the wrist.

Cat’ er pil lar, the larva of a butterfly or moth.

Caud al, pertaining to the tail.

Cell, the smallest living unit.

Cell-wall, the lifeless membrane surrounding many cells, secreted by the protoplasm.

Central cavity, the cavity surrounded by the body-wall in the simpler many-celled animals, as in the sponges.

Ceph a lop’ o da, the class to which the squid, octopus, nautilus, etc., belong.

Ceph’ al o-tho’ rax, the division of the body formed by the fused head and thorax in many arthropoda.

Cer’ vi cal groove, the groove marking the place of union when head and thorax are merged into a cephalo-thorax.

Cha la’ za, one of the spiral masses of albumen found at the two ends of a bird’s egg.

Che’ li peds, the large claws in many crustaceans.

Chor-date, animals with a notochord, present throughout life or disappearing.

Chro mat’ o phore, color body.

Chrys’ a lis, the pupa stage of a butterfly.

Cil’ i um (pl. cilia), a minute vibrating hair on the surface of many cells.

Co coon’, the envelope spun by certain larval insects in which they are inclosed during the pupa stage. A similar structure, as the egg-case of spiders, earthworms, etc.

Cœ’ cum (se’ kum), a blind pouch or bag; a sac open at one end.

Cœ len te ra’ ta, rather simple, sac-like animals with nettle cells in the body walls.

Co le op’ te ra, beetles.

Col’ o ny, a group of animals of the same kind found in one locality, usually related to each other and often actually connected.

Com men’ sal ism, an association of two animals, not mutually helpful, but without injury to either.

Com pound eye, an eye made up of many simple eyes or eye elements.

Com pressed’, narrower from side to side than from dorsal to ventral surface.

Con ju ga’ tion, a process occurring in some one-celled animals, preceding reproduction. In this process two animals unite temporarily and exchange nuclear substance, or in some forms the two cells fuse into one. After this exchange or fusion fission occurs, usually more rapidly than before.

Contracting or pulsating vacuoles, small, clear spots in a cell, filled with a watery fluid. In the living animal these alternately disappear and then reappear.

Co’ nus ar te ri o’ sus, a cone-shaped artery connected with the ventricle of the heart.

Cov’ ert, a feather overlying the base of the large feathers of the wing or tail.

Cra’ ni um, the skull, particularly that part of it inclosing the brain.

Crop, an enlarged portion of the esophagus.

Cross fertilization, a form of fertilization in which the male and female elements are produced by different individuals.

Crus ta’ ce a, aquatic, gill-bearing arthropods, with two pairs of antennæ.

Cu’ ti cle, the thin outer skin.

Cy’ to plasm, the portion of the protoplasm of a cell which is outside of the nucleus, less dense than the nucleus and usually taking a lighter stain.

Den’ ta ry, the terminal portion or bone of the lower jaw of vertebrates lower than mammals, containing all or most of the teeth.

Di a phragm, a muscular partition separating the abdomen and thorax, in mammals.

Dig’ i ti grade, walking on the toes.

Di œ’ cious, reproductive organs in different individuals.

Dip’ te ra, insects with two wings, including flies, mosquitoes, etc.

Dis’ tal end, the free end of any object which is attached by one end.

Dor’ sal surface, the upper surface; the back.

Du’ o de’ num, the first portion of the small intestine.

Ec’ to derm cells, cells covering the outside of sponges and some other simple animals.

Egg cell, the large, non-motile reproductive cell, with which a sperm cell fuses.

Em bry on’ ic, development within the egg or in the body of the mother.

En’ do derm cells, cells lining inner cavities in the many-celled animals. As a rule they have cilia or flagella.

E soph’ a gus, the portion of the alimentary canal connecting the mouth (or the pharynx) with the stomach.

Eu sta’ chi an (eu sta’ kian) tube, a passage between the pharynx and the middle ear.

Ex ha’ lent, flowing or moving away from the body.

Ex’ o skel’ e ton, an external skeleton.

Eye stalk, an appendage which bears an eye on its free end.

Fe’ mur, (1) the thigh bone; (2) the third joint of an insect’s leg.

Fer ti li za’ tion, the fusion of male and female elements in reproduction.

Fi’ bers, flexible threads; fibers of a horny material are found in the walls of many of the sponges.

Fib’ u la, the outer of the two long bones of the lower leg.

Fin, a paddle-like structure for swimming.

Fin-rays, the framework of the fins of fishes.

Fis’ sion, a method of reproduction used in all cells, by which a cell divides itself into two, usually through the center. See alsoConjugation and Budding.

Fla gel’ lum (pl. flagella), vibrating hairs larger than cilia and less numerous.

Food-balls, bits of food inside the cells of many one-celled animals, usually showing through the walls.

Food-vacuole, a small drop of water containing digestive material and a food-ball.

Fo ra’ men, an opening or short passage.

Gall-bladder, a membranous sac for the storage of gall, or bile, at the lower edge of the liver (syn. “bile sac”).

Gas ter op’ o da, the class to which the snail belongs.

Ge’ nus (pl. genera), a group of closely related species.

Germ-spot, the region in the bird’s egg in which development first takes place.

Gill, an apparatus for breathing the air dissolved in water.

Gill-cham’ ber, a pocket or cavity covered by a flap, in which the gills lie.

Gir’ dle, the name applied to the smooth band often occurring near the anterior end of an earthworm.

Giz’ zard, a portion of the alimentary canal with especially thickened muscular walls.

Glot’ tis, the opening between the vocal cords, or the mouth of the windpipe.

Gre ga’ ri ous, associations of animals with little division of labor; gathering in flocks, herds, etc.

Gullet, the inner end of the oral groove.

He mip’ te ra, insects with a piercing organ for sucking their food, Bugs.

He pat’ ic, pertaining to the liver.

Her biv’ o rous, plant-eating.

Hock, the joint of the hind leg situated between the tibia and tarsus, corresponding to the ankle in man.

Hu’ me rus, the long bone of the upper part of the arm or fore limb.

Hy men op’ te ra, order of insects to which belong bees, ants, and wasps.

Ich neu’ mon (ic nu’ mon), an insect that deposits its eggs upon or in other insects, upon which its larvæ will feed.

In ha’ lent, flowing or moving toward the body.

In ha’ lent pores, the outer ends of the canals in the body-walls of sponges.

Ink-sac, a defensive structure found in the squid.

Ju’ gu lar, pertaining to the throat.

La’ bi um, lower lip.

La’ brum, upper lip.

La mell’ i branch i a’ ta, the class to which the clam, oyster, etc., belong; bivalves, sometimes called pelecypoda.

Lar’ va, (1) the early form of an animal when it is unlike the parent, or undergoes a metamorphosis; (2) the first stage of postembryonic development.

Lat’ er al, (1) situated to one side of the median plane; (2) situated in the region of the hinge in a bivalve shell.

Lep i dop’ te ra, butterflies and moths.

Lig’ a ment, a strong band or cord binding two structures together.

Lin’ gual, pertaining to the tongue.

Lip, any structure that bounds an orifice.

Mam’ mal, vertebrates with a covering of hair or fur.

Man’ di ble, a jaw or a jaw-like mouth-part.

Man’ tle, folds of skin covering the body of a bivalve.

Masking, the covering of an animal by some object so as to hide its identity.

Max il’ læ, the appendages just back of the mandibles in arthropods.

Max’ il la ry, pertaining to or situated near the jaw.

Max il’ li peds, the appendages back of the maxillæ in crustaceans.

Me’ di an, pertaining to the middle.

Mes o gle’ a, a non-cellular layer between ectoderm and endoderm cells.

Mes o tho’ rax, the middle division of the thorax.

Met a car’ pal, one of the bones between the wrist (carpus) and the fingers (phalanges).

Met a mor’ pho sis, the series of changes which take place in the development of some animals after they are hatched.

Met a tar’ sal, one of the bones of the metatarsus, between the ankle and the toes.

Met a tho’ rax, the most posterior region of the thorax.

Mi cro nu’ cle us, see Nucleolus.

Mimicry, a method of protection due to the resemblance of an unprotected to a well-protected animal.

Mol lus’ ca, the branch of animals to which clams, snails, etc., belong.

Mo nœ’ cious, reproductive organs in different regions of the same individual.

Mouth, the anterior opening into the digestive cavity.

Neph rid’ i um (pl. neph rid’ i a), a tubule functioning as a kidney in some of the worms.

Net’ tle cells, the stinging cells found in the cœlenterates.

Noc tur’ nal, pertaining to night.

Nu cle’ o lus (pl. nucleoli), a very small, dense, dark-staining body, either within the nucleus or near it. In the latter case it is often called the paranucleus or micronucleus.

Nu’ cle us (pl. nuclei), a dense bit of protoplasm usually near the center of a cell, often staining dark.

O cel’ lus, a simple eye.

Om niv’ o rous, eating or living upon food of all kinds.

O per’ cu lum, a lid or cover.

O’ ral, pertaining to the mouth.

Oral groove, a funnel-shaped groove in one side of some one-celled animals conducting food to the mouth.

Or’ der, a term in classification used to designate a group of genera.

Or thop’ ter a, the order to which locusts, grasshoppers, etc., belong.

Os’ cu lum (pl. oscula), the large opening from the central cavity in sponges.

Os mo’ sis, the process by which fluids of different densities become equally diffused when separated by an organic membrane or by a porous structure.

Os’ ti a (sing. ostium), the inner ends of the canals in the body-walls of sponges.

O’ va ry, the organ in which the egg cells are developed.

O vi pos’ i tors, organs used to deposit eggs.

Pal’ li al, a line connecting the two muscle scars in a bivalve shell.

Palp, (1) a jointed finger-like structure on the oral appendages of arthropods; (2) oral appendages found in mollusca.

Pan’ cre as, one of the glands of the digestive system.

Par a nu’ cle us, see Nucleolus.

Par’ a si tism, an association of two animals, one living at the expense of the other.

Pec’ to ral, (1) pertaining to the thorax or breast; (2) the anterior of the paired fins of fishes.

Pelvic, (1) pertaining to the pelvis; (2) the posterior paired fins of fishes.

Pen, a remnant of exoskeleton found in the squid.

Per i car’ di um, a membranous bag surrounding the heart.

Per is so dac’ tyl, ungulates with an odd number of toes.

Per’ i to ne’ um, a membrane that lines the body cavity.

Pha’ lanx (pl. phalanges), one of the bones of the fingers or toes.

Phar’ ynx, the region of the alimentary canal just back of the mouth cavity.

Pigment, a substance which gives color to an object.

Plan’ ti grade, walking on the soles of the feet; flat-footed.

Pol’ len bas ket, the flattened hairy tibia of the hind legs of honey bees, used for carrying pollen.

Pol’ lin na tion, the transfer of pollen from the anther of a flower to the stigma.

Polyp, any radially symmetrical animal, but usually an individual in a connected colony.

Po rif’ e ra, the sponges, distinguished by the canals which perforate the body wall.

Post em bry on’ ic, development after birth or hatching.

Pos te’ ri or, situated behind or toward the hinder part.

Pro bos’ cis, a prolonged, flexible snout or a tubular structure, protruding from the head.

Pro’ leg, an unsegmented appendage found in the larvæ of some insects.

Protective resemblance, a method of protection due to the resemblance of an animal to its background.

Pro tho’ rax, the most anterior division of the thorax.

Pro’ to plasm, the living material composing the cell; the physical basis of life.

Pro to zo’ a (sing. protozoön), animals of one cell, existing alone or in loose colonies.

Prox’ i mal end, the attached end of anything which has also a free end.

Pulsating vacuoles, see Contracting vacuoles.

Pu’ pa, the stage in the development of an insect immediately preceding the adult.

Quill, one of the large, stiff, strong flight feathers or tail feathers of a bird; the hollow, basal part of a feather; a large, hollow, sharp spine.

Ra’ di al sym’ me try, having the organs or parts arranged symmetrically around a center.

Re gen er a’ tion, the power to grow new parts or organs.

Re’ gions, the principal divisions of the body, head, thorax, and abdomen.

Res pi ra’ tion, the passage of oxygen into the tissues of a living organism and of carbon dioxide out of them. These gases can pass through any thin, moist, organic membrane. When such a membrane separates two fluids which differ in the amount of oxygen they contain, oxygen passes to the fluid containing the smaller amount. The same is true of carbon dioxide. Respiration is believed to occur in all living organisms.

Ro’ dent, mammals with curved self-sharpening incisor teeth, order including mice, rats, squirrels, rabbits, etc.

Ros’ trum, a beak-like projection or snout.

Ru’ mi nant, chewing the cud.

Sac, a cavity or pouch.

Sa’ crum, a composite bone formed by the union of vertebræ in the region of hips.

Scap’ u la, the shoulder-blade.

Sep’ tum (pl. sep’ ta), a wall or partition between two cavities.

Se’ ta (pl. se’ tae), small bristles or stiff hairs.

Sex’ u al, pertaining to sex.

Si’ nus ve no’ sus, an enlargement of the termination of the large veins.

Si’ phon, a tube-like organ.

So’ mites, the serial segments or rings composing the bodies of many animals.

Spe’ ci es, a word used in classification to designate a group of animals differing only in minor details.

Sper’ ma ry, the organ in which sperm cells are developed.

Sperm cells, the small, often motile, reproductive cell, which fuses with the egg cell.

Spic’ ules, tiny needles of mineral substance found in the walls of many animals, notably sponges.

Spi’ ra cle, an opening into the tracheal breathing organs of insects.

Spire, the coiled portion of a gasteropod shell.

Spore, a cell capable of developing into a new organism.

Sternum, a bone extending along the lower middle line of the chest region.

Stom’ ach, the region of the alimentary canal especially adapted to digest food.

Stom’ ach-in tes’ tine, a region of the alimentary canal adapted to both digest and absorb food.

Sub cla’ vi an, situated beneath the clavicle.

Su’ ture, the junction of two contiguous structures.

Swim’ mer ets, the abdominal appendages in crustaceans.

Sym bi o’ sis, an association of two animals which is mutually helpful.

Tar’ sal, one of the bones of the tarsus or ankle.

Tar’ sus, (1) the ankle; (2) the fifth or terminal joint in an insect’s leg.

Ten’ ta cles, special organs for touch; also used sometimes for other purposes.

Terrifying attitudes, protective attitudes assumed by some animals.

Tho’ rax, the region of the body between the head and abdomen.

Tib’ i a, (1) the shin-bone; (2) the fourth joint of an insect’s leg.

Tooth, (1) an organ used in mastication; (2) a tooth-like projection.

Tra’ che a, a tube which carries air either to the respiratory organ or to the tissues.

Trunk, the portion of the body between head and tail.

Tu’ ber cle, a knob-like projection.

Ul’ na, that bone of the forearm which is on the same side as the little finger.

Um’ bo (pl. umbones), an elevation near the anterior end of a bivalve shell.

Un’ gu lates, hoofed mammals.

U re’ ter, a duct connecting the kidney with the urinary bladder.

U’ ro style, a long bone forming the hinder extremity of the vertebral column of tailless amphibia.

Vac’ u oles, small, clear spots in cells, filled with a watery fluid. See Food-vacuoles and Contracting vacuoles.

Valve, (1) a membranous fold which allows the blood, or other fluids, to flow in only one direction; (2) one of the two parts of the shell of a bivalve.

Vein, (1) a blood-vessel carrying blood toward the heart; (2) one of the tubular thickenings of an insect’s wing.

Ve’ na ca’ va, a large vein emptying into the right auricle of the heart.

Ven’ tral, situated on the under surface.

Ven’ tri cle, any cavity of a hollow organ, as of the brain or heart.

Ver’ mes, the worms, a poorly defined group of animals, showing bilateral symmetry but without segmented appendages.

Ver’ te bra, one of the bones of the spinal column.

Ver’ te brates, animals having a backbone.

Vi bris’ sæ, long hairs on the face.

Vis’ ce ra (pl. of viscus), the organs of one of the great cavities of the body (the abdomen, the thorax, or the cranium), usually meaning those of the abdomen.

Vi va’ ri um, a cage in which living animals are kept.

Warning colors, bright colors which render an animal free from attack.

Whorl, a single coil in the spire of a gasteropod shell.

Yolk, food material of an egg.