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[VOL. 11. 



appearance of the bundle as a whole, and the development of 

 its elements. The appearance as a whole is indicated diagram- 

 matically by the text-figures, which show especially marked 

 differences in the case of the nasturtium. In the dwarf nas- 

 turtium the fibro- vascular elements are arranged in separate 

 bundles around a central pith, while in the normal plant the 

 phloem of the different bundles has run together, making a 

 ring around the pith, the xylem being still discontinuous. 

 Bast fibers seem highly developed with thick walls, and the 

 tracheids are large, numerous, and clearly differentiated in the 

 normal nasturtium stem ; while in the dwarf stem the soft 

 bast has just begun to show signs of thickening into fibers, 

 and the tracheids are small, and comparatively few and poorly 

 differentiated. In both specimens of pea the fibro-vascular 



Nasturtium 



Pea 



FIG. 5. 



elements are arranged in an aggregate in the center of the 

 stem and in four small groups peripheral to the large group. 

 These bundles are more distinct and woody-looking to the 

 naked eye in the normal than in the dwarf plants, and both 

 bast fibers and tracheids are more numerous and highly differ- 

 entiated. The normal plant, therefore, is more highly dif- 

 ferentiated than the dwarf, as well as larger. 



The conclusions reached from macroscopic and from micro- 

 scopic examinations are then in accord with one another, and 

 may be summarized by the statement that the removing of 

 part of the cotyledons of a seed retards not merely the growth 

 in size of the plant produced from that seed, but also its 

 development. The plant, however, is not the counterpart of 

 a younger normal plant, for it was found from comparing 

 dwarf plants with check plants that the dwarf plant of a 

 certain height was further developed than the check of the 

 same height. The same point is illustrated by the fact that 



