34:6 . SIR J. LUBBOCK — rnYTOBIOLOOICAL OBSERVATIONS. 



tlie case tliey arc connected by tlie raplte. The embryo or young 

 plant consists (1) of the radicle or base of the embryo, -which 

 gives origin to the root, (2) of one or two cotyledons or future 

 seed-leaves, and (3) the plumule, or bud of the future stem bet^Nceu 

 the cotyledons. It is embedded in jy^risperm, a mealy, oily, fleshy, 

 or horn-like substance, which serves to nourish the 3'oung plant, 

 but is in many cases entirely absorbed by the embryo by the time 

 the seed is ripe. 



If we take one of the simplest seeds in a very young state, say 

 that of a Buckwheat or Xettle, we shall find that it is a small, 

 upright, more or less pear-shaped body attached at the base, 

 and with a small opening at the free end, which is called the 

 '' micropyle " or little doorway. Seeds thus formed are called 

 '* orthotropous " or straight. But this, though the simplest, is 

 the least common form of seed. More often, as in the Bean, 

 Chickweed^ and many others, the ovule during its growth is 

 curved on itself, so that the apex and the "micropyle" are 

 brought down very near to the base. Such ovules are known as 

 " campy lotropous '* or curved. 



In a third category the seed itself is straight, but it stands as 

 it were at right angles to the base of attachment. These are 



r 



called " half anatropous " or half reversed. 



Lastly, in a very large number of seeds — in fact by far the largest 

 — the seed is (piite inverted on its base; the funiculus, or stalk 

 growing with the seed, forming a sort of ridge or '' raphe " as it 

 is technically called, which is very conspicuous in the ovule, but 

 gradually becomes less and less apparent, and which completely 

 reverses the seed. The " chalaza " or plaoe of attachment of the 

 seed itself, and from which the nutritive vessels ramify, is thus 

 carried right away from the " hilum " or point of attachment 

 to the opposite end, and the whole seed is reversed, so that the 

 true base is removed from, and the true apex brought close to, 

 the j)oint of union with the ovary. Such seeds are called " ana- 



tropous or reversed. 



'Now this seems a very curious and roundabout arrangement. 

 It is described in all works on general Botany, but those which I 

 have seen do not give any explanation of its object or purpose. I 

 will for the moment omit any consideration of " campylotropous 

 and ''half anatropous" seeds, and confine myself to orthotropous 

 and anatropous forms. 



In orthotropous species, as for instance in the Buckwheat, the 



