v.J THE SEED. 47 



contents, the rest of the seed being filled with a starchy 

 albumen. 



8. The structure of this embryo we must endeavour to' 

 understand, though, in order to make it clearly out, very 

 careful sections must be made through it lengthwise. 

 The accompanying cut will supply a good idea of the 

 arrangement of its parts. We 



do not find the first leaves of 

 the embryo opposite to each 

 other, forming a pair of coty- 

 ledons, as in the Bean and 

 other Dicotyledons, but they 

 originate alternately, the outer- 

 most or lowest only being 

 spoken of as a seed-leaf or 

 cotyledon. Those wliich it 



sheaths belong tO the plumule. 



The cotyledon being single the 



embryo Of Wheat IS called mule//, and the root-buds r. 



monocotyledonous. The lower 

 part of the embryo is the radicle. 



This never directly elongates in germination, but the 

 internal, rudimentary root-buds, r> burst through it and 

 develop into the root-fibres of the plant. The process of 

 germination is similar to that of Dicotyledons, with this 

 difference in regard to the origin of the root. The sheath- 

 ing portion of the cotyledon is protruded from the seed, 

 and embraces the base of the plumule, which ultimately 

 develops into a stem. 



Now a structure similar to that of W T heat we find in 

 the seeds of other corn-plants. In Barley and Oats the 

 grain (fruit) presents a different appearance, owing to 

 the circumstance that in these plants the fruit becomes 

 adherent, after flowering, to the enclosing glume which 

 closely invests it, forming a sort of spurious pericarp 

 which is removed by grinding. The seeds of all of these, 

 however, are albuminous, corresponding, in this respect, 

 to the seed of the Buttercup. 



9. There are plants presenting so many characters in 

 common with the five last examined as to be universally 

 classed with them, although they may differ from them in 

 the absence of albumen in the seed, and in other points, 



