i8o 



BOTANICAL GAZETTE 



[FEBRUARY 



nature of the vascular system of the coleoptile, the bifid character 

 of the epiblast in some grasses, and the forked coleoptile found in a 

 few seedlings of maize. As a background for these details is the 

 idea that the monocotyledonous condition is the primitive one. 



The first piece of evidence that I have to offer on these questions 

 is in the form of a series of steps in the development of the embryo 

 of maize (figs. 1-7). These stages have often been observed and 



-C 



s 



3 





7 



Figs. 1-7. — Figs. 1-6, steps in development of embryo: C, cotyledon; S, sus- 

 pensor; Co, coleoptile; L, foliage leaf; R, root; RS, root sheath; X15; fig. 7, longi- 

 tudinal section of nearly mature embryo: 5, scutellum; Co, coleoptile; L, foliage 

 leaf; RC % root can: RS. root sheath: Su. susnensor: Xic. 



discussed more or less abstractly, but I have failed to find a complete 

 series figured. In so far as appearances may be trusted, no evi- 

 dence is clearer than this series. The appearance of the mature 

 embryo (fig. 7) leaves little doubt of the terminal position of the 

 plumule, and preceding stages of development bear this out fully; 

 the cotyledon is never terminal, even in the earliest stages. As 

 soon as the young embryo begins to differentiate, so that anything 



