88 EXPERIMENTAL PLANT PHYSIOLOGY 



Plants grown in the dark never reach maturity, but 

 wither away after a time. 



Inferences. — A seed germinates quite well in the dark, 

 and the seedling continues to grow as long as the food 

 that the parent plant has stored up for it in the seed 

 lasts; but eventually it must have light in order that 



Fig. 41 



the leaves may expand, become green, and perform 

 their work as feeding organs. The plant which is kept 

 in the dark grows excessively long in its vain attempt, 

 seemingly, to reach the light, and dies at last for lack 

 of food. 



E. Life as a Necessary Factor in Germination 



If a seed is boiled for some time in water it is no 

 longer able to germinate. Thus there is a vital differ- 



