Jurassic, a subdivision of the Mesozoic era represented in the Jura Mountains.

Karyokinesis (Gr. xáρvov, nut; xivnois, motion), mitotic or indirect cell division.

Katabolism (Gr. xaтaßoλý, throwing down), destructive metabolism.

Larva (Lat. larva, mask), an immature but active stage of an animal differing markedly from the adult.

Leucocyte (Gr. λeuxós, white; xúтos, cell), a white corpuscle of the blood.

Linin (Gr. Xívov, thread), the protoplasmic framework of the nucleus. Lipoid (Gr. Niños, fat), a substance allied to the fats.

Lymph (Lat. lympha, clear water), a clear fluid containing white corpuscles and occurring in the lymph vessels, or lymphatics.

Macronucleus (Gr. μaxpós, large; Lat. nucleus, kernel), a large nucleus, contrasted with the micronucleus.

Malaria (Italian, mal' aria, bad air), a disease characterized by chills and fever caused by a species of Plasmodium.

Mammalia (Lat. mamma, breast), a class of vertebrates which suckle

their young.

Marsupial (Lat. marsupium, pouch), an order of mammals which carry the young in a pouch.

Medusa (Gr. Médovoa, a Gorgon), a jellyfish.

Meganucleus (Gr. μéyas, large, Lat. nucleus, kernel), a large nucleus. Same as macronucleus.

Mesoderm (Gr. μéoos, middle; dépμa, skin), the middle germ layer, between ectoderm and endoderm.

Mesogloa (Gr. μéσos, middle; yλoɩá, glue), a noncellular layer in Colenterates between entoderm and ectoderm.

Mesozoic (Gr. μéσos, middle; (wn, life), the middle geological era between the Paleozoic and the Cainozoic, or Tertiary.

Metabolism (Gr. μeтaßoλý, change), the chemical transformations occurring in living substance.

Micronucleus (Gr. μxpós, small; Lat. nucleus, kernel), a small nucleus, a term used when there is a larger nucleus in the same organism as in the Infusoria.

Miocene (Gr. μeiwv, less; xawvós, recent), a subdivision of the

Tertiary era.

Mitosis (Gr. uítos, thread), indirect cell division, so called because threadlike structures make their appearance.

Monotreme (Gr. μóvos, one; тîîμa, opening), a member of the most primitive order of mammals, including the duckbill and spiny

anteater.

Morphology (Gr. μopyń, form; Xóyos, discourse), the science of

structure.

Mutation (Lat. mutatio, change), a discrete, stable germinal variation.

Nautilus (Gr. vavríλos, sailor), a cephalopod mollusc with chambered shell.

Nectary (Gr. véxтap, drink of the gods), the part of a flower that secretes honey.

Neuron (Gr. veúpov, nerve), a nerve cell with its branches.

Notochord (Gr. vŵтov, back; xopon, cord), a chord of cells forming the beginning of the backbone in vertebrate animals.

Nucleolus (Lat. diminutive of nucleus, kernel), a small, rounded body found in the nucleus.

Oligocene (Gr. ỏλɩyos, few; navós, recent), a period between the Eocene and the Miocene in the Tertiary.

Ontogeny (Gr. öv, being; yev, birth), the development of the individual.

Ordovician, a subdivision of the Paleozoic era.

Osmosis (Gr. wouós, pushing), diffusion through semi-permeable membranes.

Ovary (Lat. ovum, an egg), the organ producing eggs.

Ovule (Lat. ovulum, diminutive of ovum), the beginning seed of a flowering plant.

Ovum (Lat. ovum, an egg), an egg.

Paleontology (Gr. waλatos, old; ov, being; λóyos, discourse), the science of extinct forms of life.

Paleozoic (Gr. Taλaιós, old; (wń, life), the earliest era in which fossils are abundant although life occurred throughout long preceding periods.

Pancreas (Gr. πáv, all; xpéas, flesh), a large gland opening into the intestine and secreting the pancreatic juice.

Parenchyma (Gr. πáρeyxvμa, filling material), soft cellular tissue which is relatively undifferentiated.

Parthenogenesis (Gr. πaplévos, virgin; yéveσɩs, origin), the development of eggs without fertilization.

Pentadactyl (Gr. Tévтe, five; dáxтvλos, digit), having five digits. Peristalsis (Gr. πepɩotéλλw, I constrict), a wavelike constriction passing along a muscular tube.

Permian (from Perm in Russia), the last period of the Paleozoic

era.

Petrifaction (Lat. petra, rock; factus, made), an organism converted into stone.

Phagocyte (Gr. ❤ayeîv, to eat; xúтos, cell), a leucocyte that engulfs foreign materials.

Phloëm (Gr. λotós, bark), the outer part of a fibro-vascular bundle: it forms bark in exogenous plants.

Photosynthesis (Gr. pws, light; ovvonois, putting together), the formation of carbohydrates by green plants under the influence of light.

Phylogeny (Gr. yûλov, branch; yéveσɩs, origin), the ancestral development of a group.

Placenta (Lat. a flat cake), an organ of attachment, a term applied to the attachment of seeds to the ovary in plants, and of embryos to the uterus in animals.

Plasma (Gr. λáoμa, formative material), the fluid part of the blood or lymph.

Plastid (Gr. Tλaσrns, one who forms), protein bodies in cells which are concerned in forming certain products.

Pleistocene (Gr. πλεîστos, most; xavós, recent), the last period of the Cainozoic era.

Pliocene (Gr. πλeiwv, more; xaɩvós, recent), a late period of the Tertiary era.

Polydactylism (Gr. Toλús, many; dáxтvλos, digit), having supernumerary fingers or toes.

Preformation, the theory that the parts of the embryo are preformed in the germ.

Primates (Lat. primus, first), the order of mammals including the monkeys, apes, and man.

Prothallus (Lat. pro, in place of; thallus, young branch), the sexual generation of ferns and other flowerless plants.

Protista (Gr. Tрŵтоя, first), a group including the primitive onecelled organisms, both plant and animal.

Protophyta (Gr. πρŵτos, first; øvróv, plant), the one-celled plants. Protoplasm (Gr. πрŵτоs, first; πλáσμa, formative material), living

matter.

Protozoa (Gr. πрŵтоя, first; (@ov, animal), one-celled animals. Pseudopodia (Gr. Yeudýs, false; toús, foot), a protoplasmic projection such as occurs in an amoeboid organism.

Pulmonary (Lat. pulmo, lung), pertaining to the lungs.

Pylorus (Gr. Tuλwρós, gate-keeper), the constriction between the stomach and small intestine.

Recapitulation theory, the doctrine that individual development is an epitome of the development of the race.

Receptor (Lat. receptor, receiver), a sense organ.

Recessive (Lat. recessus, receding), not appearing in the presence of the dominant character.

Regression (Lat. regressus, going back), a return toward the mean of the group.

Renal (Lat. rena, kidney), pertaining to the kidneys.

Secretion (Lat. secretus, separated), the separation of a substance by living tissue, as when the liver secretes bile.

Segregation (Lat. segregare, to separate out), separating out.
Sepals (Lat. sepes, enclosure), the parts of the calyx.

Serum (Lat. serum, whey), the fluid of the blood after removal of the clot.
Silurian (Lat. Silures, an ancient tribe of Wales), a period of the
Paleozoic era

Somatic (Gr. oŵμa, body), relating to the body.

Spermatocyte (Gr. σñéрμa, sperm; xúтos, cell), a cell that gives rise to spermatids that develop into spermatozoa.

Spermatozoa (Gr. στéрμa, sperm; @ov, animal), mature male germ cells.

Sporophyte (Gr. σTорá, seed; Quтóv, plant), a plant which bears spores; the asexual generation.

Symbiosis (Gr. ovv, together; Bios, life), the mutually beneficial association of two species.

Synapsis (Gr. ovvays, conjunction), a pairing of chromosomes previous to reduction.

Tertiary (Lat. tertius, third), a geological era between the Mesozoic

and the Quaternary.

Thyroid (Gr. Oupéos, a shield), an endocrine gland near the larynx. Triassic (Gr. Tpiás, three), the earliest period of the Mesozoic, so

named from its three subdivisions.

Trilobite (Gr. Tpeîs, three; Xoẞós, lobe), a primitive extinct crusta

cean.

Trypsin (Gr. Tрue, to wear down), a ferment of the pancreas which digests proteins.

Urea (Gr. oupov, urine), a nitrogenous compound (NH2)2CO formed by the decomposition of proteins.

Uterus (Lat. uterus, womb), a modified part of the oviduct in which embryos are carried.

Vacuole (Lat. vacuus, empty), a space in a cell usually filled by some product of protoplasmic activity.

Vascular (Lat. vasculum, a little vessel), pertaining to vessels of some kind.

Vein (Lat. vena, vein), a vessel carrying blood toward the heart. Ventricle (Lat. ventriculus, a little belly, or venter), a cavity, es

pecially a chamber of the heart that forces blood into an artery. Vertebrate (Lat. vertebra, a joint), an animal having a backbone, or vertebral column.

Vitamine (Lat. vita, life; amin, a chemical radicle), an accessory food substance very important in maintaining life.

Viviparous (Lat. vivus, alive; parere, to bear), bringing forth living

young.

Xylem (Gr. úλov, wood), the woody part of a fibrovascular bundle.

Zoology (Gr. (@ov, animal; Xóyos discourse), the science of animals. Zygote (Gr. (vywrós, joined together), a product of the fusion of two cells in sexual reproduction.