30 FOUNDATIONS OF BOTANY 



39. Root, Stem, and Leaf. By the time the seedling is 

 well out of the ground it, in most cases, possesses the three 

 kinds of vegetative organs, or parts essential to growth, of 

 ordinary flowering plants, i.e., the root, stem, and leaf, ^ar, 

 as they are sometimes classified, root and shoot. All of 

 these organs may multiply and increase in size as the 

 plant grows older, and their mature structure will be 

 studied in later chapters, but some facts concerning them 

 can best be learned by watching their growth from the 

 outset. 



40. Young Roots grown for Examination. Roots grow- 

 ing in sand or ordinary soil cling to its particles so tena- 

 ciously that they cannot easily be studied, and those grown 

 in water have not quite the same form as soil-roots. Roots 

 grown in damp air are best adapted for careful study. 



41. Elongation of the Root. We know that the roots 

 of seedlings grow pretty rapidly from the fact that each 

 day finds them reaching visibly farther down into the 

 water or other medium in which they are planted. A 

 sprouted Windsor bean in a vertical thistle-tube will send 

 its root downward fast enough so that ten minutes' watch- 

 ing through the microscope will suffice to show growth. 

 To find out just where the growth goes on requires a 

 special experiment. 



EXPERIMENT XIV 



In what Portions of the Root does its Increase in Length take Place ? 

 Sprout some peas on moist blotting paper in a loosely covered tum- 

 bler. When the roots are one and a half inches or more long, mark 

 them along the whole length with little dots made with a bristle 

 dipped in water-proof India ink, or a fine inked thread stretched on 

 a little bow of whalebone or brass wire. 



