358 THE BIOLOGY OF THE PLANT 



Let the student make the examination with a view to 

 answering the following questions : "What is the general 

 structure of roots? "What are the most noticeable 

 structural differences between roots and stems ? How 

 do the vascular bundles of. the former compare with 

 those of the latter in arrangement and structure ? How 

 and where does the transition of root to stem take 

 place? In what way and from what tissues do the root- 

 hairs originate? How does the root grow in length? 

 In thickness ? Are the root-hairs actually attached to 

 the particles of the soil in which the plant grows? In 

 connection with this question the following experi- 

 ment is suggested : In the bottom of a box about a 

 foot square and three inches deep lay a piece of well- 

 polished marble. Fill the box with clean, damp sand, 

 and in the latter plant beans, peas, wheat, and corn. 

 After two or three weeks, by which time the roots will 

 have become well grown, empty the box, carefully wash 

 the marble, and look for the " corrosion figures " made 

 upon its surface by the roots of the seedlings. Can you 

 give any explanation of this result ? 



D.— Buds 



Material. — The best material is to be had in spring 

 before the buds expand, as then they are largest and 

 most easily examined. A series of specimens should be 

 made to illustrate the gradual growth of the buds of 

 various plants. The collection of these specimens should 

 be begun in the early summer, when the young buds of 

 next season will be found forming in the axils of the 

 leaves of the current year. Beginning with May, col- 

 lect each month from the plants named hereafter a set 

 of stems bearing thrifty buds. Put the stems for a day 



