THE STATOCYSTS OF STEMS 005 



"starch-crescents" (Starke-sicheln) occur, for example, in the nodes of 

 Grasses, where they subtend the hadrome-strands ; in the scape of 

 Arum tematum, on the other hand, they are located on the inner side 

 of the leptome-strands (Fig. 249). Occasionally these groups of 

 starch-containing cells are situated on the flanks of the vascular 

 bundles ; this occurs, for instance, in Ranunculus acris, where a 

 transverse section shows two or three, or sometimes a single statocyst, 

 on either side of each vascular bundle (Fig. 250). In Chelidonium 

 majus all the vascular bundles are enveloped in complete starch-sheaths ; 



Fio. 250. 



T.S. through one of the vascular bundles in the stem of Ranunculus acris ; the stato- 

 cysts are located on the flanks of the bundle. 



but the starch-grains of these sheaths are only large and movable 

 on the flanks of the bundles. In a few cases, finally {Tlialictnim 

 Jlavum), the functions of the starch-sheath are undertaken by the primary 

 medullary rays, the cells of which are furnished with typical statoliths. 

 It seems permissible, therefore, to assert, on the basis of the available 

 data, that all geotropically sensitive axial organs are provided with 

 a characteristic starch-sheath, or, where the latter is absent, with well 

 defined groups of cells containing movable starch-grains. 



The sensory cells of starch-sheaths, and the elements composing 

 the groups of statocysts which frequently take the place of the sheaths, 

 are always parenchymatous in character. They are not distinctly elon- 

 gated, though they may be one and a half times or twice as long as their 

 width. The advantage of this approach to the isodiametric condition 

 consists in the fact, that it facilitates the rapid transference of a large 

 number of starch-grains to the longitudinal walls, when the orsian is 



