THE AWAKENING OF THE SEED 



67 



kill the seeds in a dry condition is by heating them. 

 To avoid scorching them, we may put them on a 

 water-bath consisting of two tin-cups, as shown in Fig. 

 54. Water is placed in the lower cup, the seeds are 

 placed in the upper one and covered, and the appara- 

 tus placed on a stove. 

 After the water has boiled 

 for about an hour, the 

 seeds should be removed 

 and tested by the methods 

 previously used for live 

 seeds (some should be 

 placed in moist sawdust 

 to see if they are really 

 dead). How does the 

 pressure generated * by 

 dead seeds compare with 

 that produced by living 

 ones 1 To what extent do 

 they "grow"? Does 

 the growth become 



54. Water^bath. "Set"? 



We may, as the result of these experiments, distin- 

 guish two stages of growth, a temporary and a perma- 

 nent. The temporary stage lasts until the cell-wall 

 has been sufficiently reinforced by new material to 

 prevent it from collapsing when water is withdrawn. 



Cut off an inch from the tip of a root and of a 



