EPIDEMIC. 



ERYNGO. 



a fly could scarcel}' move but they would be 

 snatching him. See INSECTS. 



EPIDEMIC (Gr.vri and ttfw\ Fr. cpul^nnju, ). 

 In farriery, a term applied to such fevers, or 

 other distempers of cattle, as attack great num- 

 bers at certain seasons, or any time, if many 

 suffer in the same manner. The term is fre- 

 quently confounded with infections, which is 

 perfectly distinct, and implies a disease com- 

 municated, not from the atmosphere, but from 

 one individual to another. Horses are liable 

 to epidemic fevers, and to several distempers 

 of that kind, such as the epidemical catarrh or 

 influenza, strangles, staggers, &c. 



E 1' I DERMIS (Gr. tvi and <%t*, the true skin). 

 In botany, the exterior cellular coating of the 

 bark, leaf, or stem of plants and trees. It is 

 composed of cells compacted together into a 

 stratum, varying in thickness in different spe- 

 cies, and is often readily separable by gentle 

 violence. It is believed to be intended by 

 nature as a protection of the subjacent parts 

 from the drying effects of the atmosphere. 

 (Hrrnnlc's Diet, of Science.) 



EPIZOOTIC DISEASES. These prevail from 

 time to time among animals the same as epi- 

 demics among men. See VENTILATION, p. 1083. 



EREMACAUSIS (from jlgs^slow, and **i/o-<?, 

 combustion). A term applied in organic che- 

 mistry to denote one of the changes which 

 vegetable and other organic matters undergo 

 after death. 



The conversion of wood into humus, the 

 formation of acetic acid out of alcohol, nitrifi- 

 cation, and numerous other processes, are of 

 this nature. Vegetable juices of every kind, 

 parts of animal and vegetable substances, moist 

 sawdust, blood, &c., cannot be exposed to the 

 air, without suffering immediately a progress- 

 ive change of colour and properties, during 

 which oxygen is absorbed. These changes do 

 not take place when water is excluded, or when 

 the substances are exposed to the temperature 

 of 32 ; and different bodies require different 

 degrees of heat, in order to effect the absorption 

 of oxygen, and, consequently, their eremacau- 

 sis. The property of suffering this change is 

 possessed in the highest degree by substances 

 which contain nitrogen. 



The decay of woody fibre (the principal con- 

 stituent in all plants) is accompanied by a 

 phenomenon of a peculiar kind. This sub- 

 stance, in contact with air or oxygen gas, con- 

 verts the latter into an equal volume of carbonic 

 acid, and its decay ceases upon the disappear- 

 ance of the oxygen. If the carbonic acid is 

 removed, and oxygen replaced, its decay re- 

 commences, that is, it again converts oxygen 

 into carbonic acid. Woody fibre consists of 

 carbon and the elements of water ; and if we 

 judge only from the products formed during 

 its decomposition, and from those formed by 

 pure charcoal, burned at a high temperature, 

 we might conclude that the causes were the 

 same in both : the decay of woody fibre pro- 

 ceeds, therefore, as if no hydrogen or oxygen 

 entered into its composition. 



In the Appendix to the Third Report of the 



Agriculture of Massachusetts, 1840, Dr. S. L. Dana 



adduces the following example, to show that 



even a moist plant will not decay, if air is ex 



446 



eluded. A piece of a white birch tree vas 

 taken from a depth of twenty-five feet tlow 

 the surface, in Lowell. "It must have been 

 inhumed there probably before the creation of 

 man, yet this most perishable of all wood is 

 nearly as sound as if cut from the forest las< 

 fall." 



A very long time is required for the comple- 

 tion of this process of combustion, and the pre- 

 sence of water is necessary for its maintenance: 

 alkalies promote it, but acids retard it ; all an- 

 tiseptic substances, such as sulphurous acid, 

 the mercurial salts, empyreumatic oils, &c., 

 cause its complete cessation. 



Woody fibre, in a state of decay, is the sub- 

 stance called humus. 



The property of woody fibre to convert sur- 

 rounding oxygen gas into carbonic acid dimi- 

 nishes in proportion as its decay advances, 

 and at last a certain quantity of a brown coaly- 

 looking substance remains, in which this pro- 

 perty is entirely wanting. This substance is 

 called mould it is the product of the complete 

 decay of woody fibre. Mould constitutes the 

 principal part of all the strata of brown coal 

 and peat. (Liebig's Organic Chemistry.') 



The eremacausis or putrefaction of sub- 

 stances containing nitrogen, is the process 

 technically called nitrification. 



ERGOT (Spermcedia clavus). A parasitic 

 fungus, which most frequently appears upon 

 the ears of rye, but sometimes upon other 

 plants of the gramineous order. It most com- 

 monly appears in hot, damp summers. It is 

 known to be present by the change which the 

 affected grains assume ; but these seldom ex- 

 ceed five or six in an ear. The grain length- 

 ens to more than double its natural size, be- 

 comes angled, of a deep purplish-brown colour, 

 and curved at its apex, where the ergot is seat- 

 ed. The surface, when viewed through a mag- 

 nifying glass, appears studded with transparent, 

 shining, white, angular dots ; and when sliced 

 and viewed in water under the microscope, it 

 is seen to consist of white, flocculent threads, 

 bearing globular sporules. The ergotted grains 

 have a heavy, unpleasant odour, and an acrid, 

 nauseous taste, leaving a slight sensation of 

 heat in the palate. Ergotted rye is poisonous 

 both to man and other animals. When, in bad 

 seasons, it has prevailed, and has been ground 

 into flour with the rye, and baked in bread, it 

 has caused many fatal depopulating epidemics 

 in the north of Europe. On quadrupeds its use 

 is followed by emaciation, palsy of the hind' 

 legs, and extreme debility; mules in South 

 America lose their hoofs and hair when fed on 

 ergotted maize; and hens who have ergotted 

 rye mixed with their food, lay eggs without 

 shells, owing to its excitement of the oviduct. 

 It is employed as a medicine in difficult partu- 

 rition, but it ought not to be administered with- 

 out the greatest caution and discretion. (Edin. 

 J\fr>l. ,i)ifi Svrg. Journ. vol. liii.) See MILDEW. 



ERICA VULGARIS. The common heath, 

 ling, or heather. See HEATH. 



ERIOPHORUM. The genus of cotton grass- 

 es, which see. 



ERYNGO (Eryngium). A genus of plants 

 consisting of eleven species, two of which are 

 perennials, natives of England, viz., 1. The -iea 



