OF THE COTYLEDONS.

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the root makes more or less of a curve in order toshoot downwards. Mr. Hunter sowed a number ofseeds in a basket of earth placed on an axis, by whichtheir position was a little altered every day. Afterthe basket had thus made two or three circumvolu-tions, the young roots were found to have formed asmany turns in attempting to attain their natural per-pendicular direction. Mr. Knight has ascertained,Phil. Trans, for 1806, that astrong centrifugal force,applied to vegetating seeds, will considerably divertthe root from this direction outwards, while the stemseems to have a centripetal inclination.

The young root, if it grew in a soil which affordedno inequality of resistance, would probably in everycase be perfectly straight, like the radical fibres ofbulbous roots in water ; but as scarcely any soil is soperfectly homogeneous, the root acquires an unevenor zigzag figure. It is elongated chiefly at its extre-mity*, and has always, at that part especially, moreor less of a conical or tapering figure.

When the young root has made some progress, thetwo lobes, commonly of a hemispherical figure, whichcompose the chief bulk of the seed, swell and expand,and are usually raised out of the ground by the as-cending stem. These are called the Cotyledons,/. 4.Between them is seated the Embryo or germ of theplant, called by Linnaeus Corculum, or little heart, in

* As may be seen by marking the fibres of Hyacinth roots in water,or the roots of Peas made to vegetate in wet cotton wool.