52 WONDERS OF PLANT LIFE 



activity for many years. Finally, when digging 

 operations have brought them more near the 

 surface, they have readily germinated, apparently 

 little the worse for their long confinement. 



Granted certain conditions, the seed will 

 speedily show signs of development. Warmth, 

 moisture, and the presence of oxygen soon stir 

 the sleeping embryo into life, and bring about the 

 wonderful changes connected with the birth of the 

 plant. Heat is necessary for the forwarding of 

 all vital processes ; moisture is required for the 

 conversion of the nutrient into a fluid state, whilst 

 oxygen is necessary in order to bring about the 

 change of the starch into sugar, in which form it 

 can be assimilated by the plant. In a chemical 

 sense, starch and sugar are not widely different, 

 save that the former contains an additional pro- 

 portion of carbon. The absorption of oxygen by the 

 seed sets free some of the carbon, and thus changes 

 the composition of the food supply. At first sight 

 it may seem strange that in the beginning sugar 

 was not stored away in the seed. It is a wise 

 provision that has ordered it otherwise, for had 

 sugar been deposited in the first instance it would 

 almost certainly have undergone fermentation. 

 In this condition it would, of course, have been 

 useless for the nourishment of the little plant. 



