HOW PLANTS OBTAIN THEIR FOOD. 



99 



206. Structure of the pumpkin seed. The pumpkin seed has 

 a tough papery outer covering for the protection of the embryo 

 plant within. This covering is made up of the seed coats. 

 When the seed is opened by slitting off these coats there is seen 

 within the "meat" of the pumpkin seed. This is nothing 

 more than the embryo plant. The larger part of this embryo 

 consists of two flattened bodies which are more prominent than 

 any other part of the plantlet at this time. These two flattened 

 bodies are the two first leaves, usually called cotyledons. If we 

 spread these cotyledons apart we see that they are connected at 

 one end. Lying between them at this point of attachment is a 

 small bud. This is the plumule. The plumule consists of the 

 very young leaves at the end of the stem which will grow as the 

 seed germinates. At the other end where the cotyledons are 

 joined is a small projection, the young root, often termed the 

 radicle, 



207. How the embryo gets out of a pumpkin seed. To see 

 how the embryo gets out of the 1 pumpkin seed we should 

 examine seeds germinated in the folds of damp paper or on damp 

 sphagnum, as well as some which have been germinated in earth. 

 Seeds should be selected which represent several different stages 

 of germination. 



Fig. 88. 



Germinating seed of pumpkin, showing how the heel or " peg 

 to cast it off. 



catches on the seed coat 



208. The peg helps to pull the seed coats apart. The root 

 pushes its way out from between the stout seed coats at the 

 smaller end, and then turns downward unless prevented from so 



