THE FLOWERING PLANTS. 17 



This is not always the case ; a considerable variety of 

 arrangements occur. Using seeds of common plants, 

 soaking them over night, cut through so as to show the 

 location of the embryo, which will sometimes be found 

 imbedded in the stored-up food, and sometimes situated so 

 as to inclose it. When the stored-up food is not in the 

 cotyledons, it is known as albumen or endosperm. Seeds 

 containing it are albuminous ; those not containing it are 

 exalbuminous. Draw all the different types found. Dis- 

 sect out some of the embryos whole. Seeds of Four- 

 o'clock, Poppy, Barberry, Asparagus, Locust, Spring 

 Beauty, and numerous other plants will serve for these 

 observations. 



5. Trace the development of the radicle in seedlings 

 of different ages. What is the direction of its growth? 

 Place on their sides seedlings that have well-developed 

 radicles, covered in moist sawdust, so that their radicles 

 and plumules point horizontally. In twenty-four hours 

 examine. The radicles have obeyed an influence which 

 has turned them towards the center of the earth. This 

 influence is believed to be the attraction of gravitation ; 

 its manifestation is called geotropism, and the movement 

 is a geotropic movement. 



6. As the radicles grow, do they branch ? If so, is 

 there any uniformity in the mode of branching ? Do any 

 of the radicles develop into a taproot, i.e., a root that 

 grows straight towards the center of the earth ? If there 

 is a taproot, where do the secondary roots, i.e., those that 

 form after the primary root has become well started, have 

 their origin ? 



7. Near the tip ends of the youngest roots find with a 

 magnifying glass minute hairs. Do they cover the tip of 

 the root ? If not, about how far from the tip do you find 

 them ? As the roots increase in age, the hairs die away, 

 and new ones are formed on the newer portions of the root. 



CLARK'S EOT. 2 



