170 The Primary Structure of the Stem of Catamites. 



Catamites, we find little in its structure to elucidate the 

 nature of the tissue under consideration. Strasburger 

 mentions 1 that in Equisetum maximum tannin bearing 

 elements are scattered in the ground tissue, both of the 

 stele and the cortex, and that they are elongated structures 

 arranged in longitudinal series. These, however, are scarcely- 

 comparable with the elements of the inner cortical zone of 

 Catamites, though they are not unlike the groups of cells 

 with black contents, sometimes seen in the pith. 



For the present, then, we may leave the interpretation 

 of this peculiar tissue an open question, in the hope that 

 further specimens may soon be forthcoming to throw 

 additional light upon it. 



EXPLANATION OF THE FIGURES. 



Fig. 1. Transverse section of the Stem of a young Catamites. 



a. Peripheral portion of the pith. 



fr, c. Narrow and broad ridges respectively at the surface of 

 the stem. 



d. Carinal canals of primary vascular bundles. 



v. Carinal canals with projecting vascular elements. 



p. Phloem of primary vascular bundles. 



s. Boundary between the stele and the cortex. 



/, 0. Inner and outer zones respectively of the cortex. 



m. Elements of inner cortical zone with black contents. 



n. Smaller elements of inner cortical zone. 

 Fig. 2. Transverse section of Stem of Catamites with secondary 

 thickening. 



a. Pith. 



d Carinal canals of primary vascular bundles. 



x. Secondary xylem. 



r. Medullary rays. 



t\ 0. Inner and outer cortical zones respectively. 



/. Lacunae in the outer cortical zone. 



s. Sclerenchyma of do. do. 



1 Histologische Beitrage, Heft III., p. 433. 



