19 



will stand still in a very liberal sense of that term for an indefinite 

 time, not weeks, but long months. 



The last type of plant to be considered is represented here by 

 the common sunflower {He&anthus animus L.). As with the 

 other types, the plants in alternate rows were de-plumuled. The 

 first change was quickly observed, namely, the enlargement of 

 the cotyledons ; but here the most noticeable thing observed was 

 the elongation of the hypocotyl, which finally reached fully nine 

 inches or double that of the normal plants. There is a greater ten- 

 dency for hypocotyledonary growth in the sunflower than in any 

 other of the types named, and this was remarkably accentuated 

 in the mutilated plant. The structure of this stem, even at the 

 end of three months, retained generally the primitive structure it 

 possessed as a young seedling, that is, for example, the wood 

 zone was made of a series of stout bundles, evenly disposed with- 

 out the filling in and completion of the thick ring of xylem so 

 well demonstrated in the normal plant at the same age. 



The experiments illustrate how an organ normally designed to 

 store food for the developing seedling may persist in case of an 

 emergency and take on a greatly increased size for that purpose. 

 The petiole may assume a direction in connection to its enlarge- 

 ment that will aid the blade in its work of photosynthesis. Along 

 with these changes in the seed-leaves there may be others in sur- 

 rounding parts, particularly the hypocotyl when it becomes thick- 

 ened remarkably and green as in the morning glory and greatly 

 elongated but slender as in the sunflower. In case of the radish a 

 place for any surplus growth is provided for in the root, naturally 

 destined to be fleshy and the hypocotyl is not modified. 



Perhaps the greatest surprise is the length of time a plant will 

 hold out when it is deprived of the means for making a success- 

 ful struggle for life and of all possibility of reproduction. 



Rutgers College, New Brunswick, N. J. 



