THE GROWTH OF THE PLANT 91 



Observations. — 1. ^Mien the seed is planted so that 

 the radicle points downwards, the radicle grows verti- 

 cally downwaMs and the plumule verticaUy upwards 

 (Figs. 42 and 43). 



2. If the radicle of the seed is made to point up- 

 wai-ds when planted, the radicle grows upwards for a 

 Uttle way, it then bends right over and grows down- 

 wards; the plumule cui-ves and irrows upwards CFiss. 

 42 and 44). = F V o 



3. When the radicle of the seed points horizontally 

 it grows horizontally for a little waj' ; it then bends at 

 right angles and grows downwards ; the plumule grows 

 upwards (Fig. 42). 



Inferences. — The plumule always ultimately grows 

 straight upwards and the radicle straight downwanis 

 whatever the position in which the seed is planted. 



(Xofr. — Method (b) of the above experiment is one 

 that will constantl}- be found useful when early stages 

 of growth are under investigation.) 



Experiment .", 



Aim. — To find out whether light aftects the direction 

 of growth taken by the shoot. 



Method. — A wooden box — a margarine box is suit- 

 able for the purpose — is painted black on the outside 

 and lined with black paper. A small hole is made in 

 the cover of the box near one end. The box then 

 stands on one of its shorter sides and a small pot con- 

 taining a sunflower seedling is put inside. 



It will be neeessiiry to remove the cover at intervals 

 in order to water the developing seedling, but care must 

 be taken not to ;Uter the position of the pot. 



If the cover does not fit exactly, black paper should 

 be pasted round the edges of it. 



The box must then be placed in a good hght. 



The seedling is now illuminated from one point only. 



(See also the method used in Experiment 59.) 



