Abscissa

The line forming the basis of measurement of graphic records, along which the time measurement is usually made.

Accommodation

Focusing the eye for different distances; it is effected by the lens becoming more convex for near objects, owing to the ciliary muscle drawing forward its choroidal attachment, and relaxing the suspensory ligament.

Acinous Glands

Secreting organs composed of small saccules filled with glandular epithelium connected with the twigs of a branched duct.

Adenoid Tissue

A delicate feltwork of reticular tissue containing lymph corpuscles (Lymphoid tissue).

Adequate Stimulus

The particular form of stimulus which excites the nerve endings of a special sense organ.

Afferent Nerves

Those bearing impulses to the nervous centres from the periphery to excite reflex actions or stimulate the sensorium.

Agminate Glands

A name applied to the lymph follicles occurring in groups in the lower part of the small intestine.

Albumins

A term derived from the Latin for white of egg (Albumen), denoting a group of complex chemical substances obtained from ova, blood plasma and many tissues of animals and plants.

Albuminoids

A class of nitrogenous substances allied to the albumins in composition, but differing from them in many important respects.

Allantois

A vascular outgrowth from the embryo; in mammals it helps to form the placenta, and in the chick forms the respiratory organ.

Alveoli

The term used to denote small cavities found in many parts, such as the air spaces of the lungs. Amnion. The membranous sac which grows around the embryo and encloses the fcetus, etc., during its development.

Amoeba

A unicellular organism consisting of a nucleated mass of protoplasm.

Amorphous

Without definite or regular form; the opposite of crystalline.

Ampulla

A dilatation on the semicircular canals of the ear.

Amylolytic

Relating to the conversion of starch into dextrine and grape sugar.

Amylopsin

A ferment in the pancreatic juice, which converts starch into sugar.

Anabolic

An exciting influence exerted by nerves increasing the metabolism of tissues.

Analgesia

A condition of the nervous centres in which pain cannot be felt, but tactile and other sensations remain unimpaired.

Analysis

A separation into component parts; the splitting up of a chemical compound into its constituents.

Anastomoses

The direct union of blood vessels without the intervention of a capillary network.

Anelectrotonus

An electric condition of a nerve, resulting from the passage of a current through a part of it; it is confined to the regions of the positive pole.

Anode

The positive pole or electrode - i.e., the pole by which the electric current enters.

Apncea

A state of cessation of the breathing movements from non-excitation of the respiratory nerve centre.

Area Opaca

The outer zone of the part of the blastoderm from which the foetal membranes are developed.

Area Pellucida

The central spot of the part of the blastoderm from which the embryo chick is developed.

Arteriole

A small artery; usually applied to those vessels the walls of which are largely composed of muscle tissue.

Arthroses

Movable joints having a synovial membrane.

Asphyxia

Literally, cessation of the pulse, such as occurs from interruption of respiration, now used as synonymous with suffocation.

Assimilation

The chemical combination of new material (nutriment) with living tissues. Power to assimilate forms the most characteristic property of living matter.

Astigmatism

Unevenness of the refracting surfaces of the eye; when engaging the entire cornea it is called "regular," and affecting a local part, "irregular," astigmatism.

Atoms

The ultimate indivisible particles of matter.

Atrophy

A wasting from insufficient nutrition.

Automatic

Self-moving - i. e., acting without extrinsic aid; a term applied to the independent activity of certain tissues (such as the nerve centres), the exciting energies of which are not readily determined.

Axis Cylinder

The essential conducting part of a nerve fibre, composed of fine strands of protoplasm.

Bacteria

A class of minute fungi occurring in decomposing animal or vegetable substances.

Bilirubin

The red coloring matter of the bile of man and carnivora.

Biliverdin

The greenish coloring matter of the bile of herbivorous animals.

Binocular

Pertaining to vision with two eyes. A combination of the effect of two retinal impressions bymeans of which the appearance of distance and solidity are arrived at.

Biology

The science of life, including morphology and physiology.

Blastoderm

The primitive cellular membrane formed by the segmentation of the ovum, in a part of which the embryo is developed.

Blood Pressure

The force exercised by the blood against the walls of the vessels. It is very great in the arteries, and therefore causes a constant stream through the capillaries to the veins.

Canaliculi

Minute channels connecting the small cell spaces or lacunae of bone, and containing protoplasmic filaments uniting the neighboring cells.

Carbohydrates

Compounds of carbon, hydrogen and oxygen, in which the oxygen and hydrogen exist in the proportions requisite to form water.

Cardiograph

An instrument by means of which the heart's impulse is transmitted, through an air tube, from a tambour on the chest wall to another which makes a record on a moving surface by means of a lever.

Catelectrotonus

An electric state of nerve in the region where the current leaves the nerve, i. e., near the negative pole.