180 Sargant and Arber.— The Comparative Morphology of 
members, we find them meeting each other and the coleoptile at the 
first node. Then the coleoptile of such a form would clearly bear the same 
relationship to its cotyledon as the ‘ axillary stipule ’ of Potamogeton to its 
own leaf. 
The epiblast is membranous and very well developed (PI. IX, Fig. 6). 
The primary root is less vigorous than that of Avena , and no cauline roots 
I. II. 
Text-fig. 19. Zizania aquatica , L. Structure of axis in seedling shown in a series of diagrams 
representing transverse sections from above downward. I. The coleoptile bundles P and P' are 
shown in the cortex. G— root-girdle; r ± , r 2) r 3 , adventitious roots. II. The coleoptile bundles 
are dividing and fusing to form the scutellum bundle sc. and the bundle x, which passes down the 
mesocotyl in the stele. Ill and IV. Mesocotylar stele completely formed. M — midrib of 
first leaf. 
are formed from the insertion zone just above it. They are produced, 
however, at all the early nodes, which are crowded together at the base of 
the plumule. 
The scutellum contains a single slender bundle, running down the 
dorsal ridge to the zone of insertion. Here, as in Avena , the scutellum 
bundle enters the axis and at once turns sharply upwards, travelling to the 
first node side by side with the stele. Throughout its course in scutellum 
