1920] 



PRA N K ERD—S TA TOCY TES 



151 



t 



The recognition of the node as indeed a definite sense organ 

 of gravity perception on the part of the wheat plant readily accounts 

 for the presence of starch in this region when the ear is ripe, which 

 otherwise seems difficult of explanation. 



I would further suggest the possibility that in the course of 

 evolution the wheat plant may be substituting a body, metaboli- 

 cally harmful, but heavier and therefore quicker and better as a 



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ilcrrryis 



■ ■ coilerK.foyn7a 



* 



T fibrous stra.rjd$ 



. va&cu Im* shranci 





res 



Xyleii7 



&VuVociitt't 



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CrysYa\ - 



Fig. 1 



Fig. 2 



S3 



Q 



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Fig. 3 



Fig. 4 



Figs. 1-4. — Fig. 1, part of transverse section (diagrammatic) across node of 

 wheat stem, showing position of statenchyma: heavily dotted line, amylostatenchyma; 

 lightly dotted line, crystal statenchyma; X 20; fig. 2, portion of fig. 1 enlarged to show 

 structure; X70; fig. 3, portion of crystal statenchyma in longitudinal section; X 140; 

 fig. 4, various forms of crystal statoliths; X620. 



statolith, for the usual starch grain, which is required as nutriment 

 for the ear. If this be true for grasses in general, it may be one 

 of the many subtleties of structure that have contributed to the 

 extraordinary success of the group. I am not without hope that 

 future work may not only establish the nodes of the wheat plant 



