GEO 



GES 



GEOLOGY (from j-??, and Xoyog, a 

 discourse). The science which in- 

 vestigates the present appearance of 

 the earth's surface, and the changes 

 to which it has been subjected. The 

 earth's crust is divided into four great 

 divisions : 1st. The primitive period, 

 epoch, or era, consisting of massive 

 crystalline rocks. 2d Tlie transition 

 period and era, containing paving 

 stones with few fossils, but stratitied. 

 3d. Secondary rocks, less condensed, 

 and containing many fossils. 4th. 

 The tertiary period, era, or epoch, 

 which consists of strati arranged in 

 extensive basins, and contains many 

 recent fossils. Besides these, drift 

 materials, called diluvion, and the 

 deposites of lakes and rivers, termed 

 alluvion, cover extensive tracts. The 

 causes producing change are, for the 

 most part, those now in existence, 

 as winds, the sea, rivers, vegetable 

 and animal growth, volcanoes, ice- 

 bergs, glaciers, bursting of lakes, 

 &c. See the geological terms ; also 

 Springs, Drainage. 



The study of geology is interesting 

 to the farmer in furnishing him with 

 certain rules for drainage, the deter- 

 mination of springs, and of the quali- 

 ty of soils. 



G E O .\I E T E R S. Span worms. 

 Caterpillars destructive to foliage. 



G E O .M E T R Y. The science of 

 measures. 



GEORGIA BARK. The bark of 

 the Pinckneya puhens, a handsome 

 tree of Florida. 



" The wood of the Georgia bark is 

 soft, and unfit for use in the arts ; 

 but its inner bark is extremely bitter, 

 and appears to partake of the febri- 

 fuge virtues of the Cinchona, for the 

 inhabitants of the southern parts of 

 Georgia employ it successfully in the 

 intermitting fevers which, during the 

 latter part of summer and autumn, 

 prevail in the Southern States. A 

 handful of the bark is boiled in a quart 

 of water till the liquid is reduced one 

 half, and the infusion is administered 

 to the sick From the properties of 

 its bark the Pinckneya has taken the 

 name of Georgia bark. The tree 

 which produces it so nearly resem- 



bles the Peruvian vegetable, that 

 some botanists have included them 

 in the same genus." — (Michaux.) 



GERM. The vital part or em- 

 bryo. 



GERMEX. The seed vessel, ova- 

 rium. 



GERMINATION. The sprouting 

 of seed. For its production, a tem- 

 perature above 60° Fahrenheit, ac- 

 cess of oxygen, and moisture are ne- 

 cessary ; by hindering any of these, 

 it will not take place, but the seed 

 remains unchanged or rots. In ger- 

 mination moisture is first absorbed, 

 and then oxygen : the latter, acting 

 on the substances of the seed, pro- 

 duces carbonic acid and heat; starch 

 becomes changed into a saccharine 

 matter, and movements, resembling 

 circulation, occur. The germ, ex- 

 panding in both directions, puts out 

 a root and seed leaves. Whatever 

 hastens these changes assists germi- 

 nation ; hence steeping in warm wa- 

 ter, planting in loose soils near the 

 surface, and securing a high tempera- 

 ture, all advance sprouting. Dark- 

 ness is in some degree favourable to 

 germination. 



GESTATION. The period ani- 

 mals carry young. 



•' According to the observations of 

 M. Teissier, of Paris, in 582 mares, 

 which copulated but once, the short- 

 est period was 287 days, and the 

 longest, 419 ; making the extraordi- 

 nary difference of 32 days, and of 89 

 days beyond the usual term of eleven 

 months. The cow usually brings 

 forth in about nine months, and the 

 sheep in five. Swine usually farrow 

 between the 120th and 140th day, be- 

 ing liable to variations, influenced, ap- 

 parently, by their size and their par- 

 ticular "breeds. In the bitch, on the 

 contrary, be she as diminutive as a 

 kitten, or as large as the boarhound, 

 pupping occurs on or about the 63d 

 day. The cat produces either on the 

 55th or 56th day. The true causes 

 which abridge or prolong more or 

 less the perioil of gestation in the fe- 

 males of quadrupeds, and of the in- 

 cubation of birds, are yet unknown 

 to us. 



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