THE SEED 63 



what conditions must be fulfilled in order that the 

 embryo may make use of these stores, may bring into 

 circulation this sunk capital. 



These conditions are well known. Water is needed 

 — for the seed does not germinate in dry soil ; heat is 

 needed — for a seed sown during a cold spring does not 

 show any sign of development until the sun warms it ; 

 lastly, air is needed — for a seed buried deeply in the soil 

 may remain very long without germinating. 



Thus water, heat, and air are the three essential 

 conditions which awaken the seed to life. Let us in- 

 vestigate them in turn. 



First of all water. Seeds generally contain very little 

 water (see table on p. 43). This is one of their essential 

 peculiarities. A seed which is not dry loses its most 

 important property — the power of concealing life, of 

 living through winters, years, and even centuries in a 

 dormant condition. If the seed is not dry it cannot be 

 preserved ; we cannot get good seed in a wet autumn — 

 grain then germinates in the sheaves or even before the 

 corn is cut. For a seed to remain in the resting state 

 the principal condition is thus the absence of water. 

 As soon as the seed is brought into contact with water 

 we notice an immediate awakening to life. The seed 

 swells and breaks the seed-coat which protected it. 



This' absorption of water is generally accompanied by 

 a considerable manifestation of energy. An English 

 scientist named Hales studied this phenomenon as early 

 as the beginning of the eighteenth century. He filled 

 a small iron pot with moistened beans, and covered 

 them with a lid upon which he placed a weight. He 

 proved in this way that bean seeds as they swell can 

 lift nearly two hundred pounds. Hofmeister has 

 demonstrated that seeds swelling under similar circum- 

 stances exercise on the walls of the vessel containing 



