E.E.G. (Electroencephalogram). Record of the rhythmical changes in electrical potential occurring in vertebrate brain, mainly cerebral cortex, which can be detected through intact skull. Patterns in man can be correlated with various physiological and pahtaological states such as epilepsy.

Eelworms. Nematodes applied only to plant – parasitic and free living forms.

Effector. A cell or organ that produces a physiological response when stimulated by a nerve impulse. Example include muscles and glands.

Efferent. Carrying (nerve impulses, blood, etc.) away from the centre of a body or organ towards peripheral regions. The term is usually applied to types of nerve fibres or blood vessels.

Effusion.
If refers to moving out of pus, blood, lymph, serum, etc., into the body cavity due to inflammation or due to excess blood or tissue fluid in an organ.

Elasmobranchii. Often synonymous with Chondrichthyes, (q.v.). Sometimes made a sub-class of Chondrichthyes, including all members of this class except Holocephali.

Elastic cartilage. A cartilage in which fibres are found in the matrix. It is present in the pinna, epiglottis and tracheal rings.

Elastin. A fibrous protein in the form of highly extensible and elastic fibres (‘yellow fibres’) found sparsely scattered in vertebrate connective tissue; numerous in some places, e.g. in lungs, walls of large arteries.

Elater.
(1) Elongated cell with wall reinforced internally by one or more spiral bands of thickening, numbers of which occur among spores in capsules of liverworts; assist in discharge of spores by their movements in response to changes in humidity.
(2) Appendage of spores of horsetails; formed from outermost wall layer, coiling and uncoiling as air is dry or moist, possibly assisting in spore dispersal.