THE ROOT 35 



in position with some cotton-wool. After a day or so 

 remove the seedlings, and gently wash them in some 

 clean water to remove any colouring matter on their 

 outside. Then cut them lengthwise and across. Note 

 that the one placed in the weak eosin or red ink has 

 become red inside, whilst the one from the carmine has 

 not. The explanation of this difference is to be found 

 in the fact that eosin and red ink are soluble in water, 

 whilst carmine is not, but remains in the water as very 

 fine, solid particles. The red solution can pass into the 

 roots, but it is not possible for any solid particles, how- 

 ever small, to make an entry. 



This experiment has a very important bearing on 

 the question of the relative value of manures and other 

 forms of plant food. 



Roots and Gravitation. 



Take a wide-mouthed square bottle of clear glass (for 

 instance, a sweet-bottle) and pour in it a small quantity 

 of water. Obtain a good cork to fit the bottle, and pass 

 through it a fine knitting-needle. Take a bean which 

 has been allowed to germinate in damp sand or sawdust, 

 and has a root about one inch long, and fix it on the end 

 of the knitting-needle so that its root points downwards. 

 Place the cork with the bean in the bottle, and allow it 

 to remain for twelve hours. The root continues to 

 grow straight downwards. Now lay the bottle on its 

 side, when the root will lie horizontally. Examine at 

 frequent intervals (for instance, of two hours), and note 

 that the direction of the root changes, the tip soon 

 curving round until it comes to point vertically down- 



