Minnesota Plant Life. 



431 



in size, and nutrition, meaning by tliat, increase in snbstance. 

 Plant stems usually become more extended in the dark than in 

 the light. Thus, if potatoes are allowed to sprout in the cellar 

 the stems produced under such circumstances are quite different 









Fig. 215. — Jack-in-the-pulpit. A .shade plant. After photograph by Hibbard. 



in appearance from those grown in the ordinary way. Con- 

 sequently, the principal hours of growth are those of the night, 

 and corn-staiks, if carefully measured, will be found to increase 

 in length most rapidly between midnight and morning. 



