io Lang, Morphology of the Stock of Isoetes lacustris. 



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/''4'-. 2. — Outlines of selected sections of a transverse series 

 through a stock of Isoetes lacustris. In this and the three following 

 figures the primary stele of the stem and rhizophore is black. The 

 line outside this marks the position of the secondary meristem, the 

 prismatic tissue occupying the position of the space between this and 

 the primary stele. The leaf-traces and root-traces are shown in the 

 cortex. Further description in the Text. 



(The outlines in this figure and in Figs. 3, 4, 5, were obtained 

 by drawing over photographs and then destroying ihe photographic 

 picture, leaving the outline.) 



