54 SEEDS 



micropyle. Remove the testas and compare the embryos part- 

 by part. Which have thick seed leaves? In which are the 

 seed leaves thin? (Dodder has none.) In which are there, 

 more than two? In which seeds is there an endosperm? 

 What relation seems to exist between the size and thickness 

 of seed leaves and the amount of endosperm? In which 

 is the plumule (first bud) large and distinct ? 



Conclusion. State what parts are found in all seeds and 

 the relation which exists between the size of plumule and 

 thickness of seed leaves. 



40. SEEDS WITH FOOD OUTSIDE THE EMBRYO 

 Object. To find out the structure of castor beans. 

 Apparatus. Several large castor beans. 



Method. Study the outside of the castor bean as before. 

 Then carefully crack the brittle shell by giving it a little 

 tap with a pencil. 



On removing the testa notice the thin inner skin which 

 covers the kernel of the seed, (a) Run a pin around the 

 edge, being careful not to penetrate too, far into the kernel. 

 Separate the two halves and find the embryo as it lies em- 

 bedded in the food (endosperm). (6) Select another seed, 

 and having removed its testa as before, cut it lengthwise 

 through the middle. Note the embryo as it lies buried in 

 the thick endosperm. 



How many seed leaves do you find? Are they thick or 

 thin? Large or small? Find the pointed end. Can you 

 find a bud between the seed leaves ? 



Examine the food (endosperm). Note its thickness. 

 Test it for oil by crushing on unsized paper. 



Conclusion. State in one or two sentences the peculiar- 



