4° The Botanical Gazette. [February, 



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the young tracheae, and in this species are especially noticea- 

 ble (fig. 1, tr\ 



Osmunda Claytoniana. — On comparing the roots of this 



species with the foregoing, we are struck first by their 

 smaller size; and on examining the growing-point, the cells 

 show a corresponding decrease in size, as well as greater reg- 

 ularity in the divisions of the apical cell and its segments. 

 As in O. cinnamomea, the apical cell appears in vertical sec- 

 tion deeply triangular, or occasionally truncate below. In 

 one case (fig. 5), which closely resembles Bower's figures, 10 

 and 14- 1 , two cells of very similar appearance occupied the 

 growing point, but the smaller of these two, x', was proba- 

 bly a segment of the larger one, .r, which is to be regarded 

 as the real apical cell. In transverse sections, a single, four- 

 sided cell was met with in nearly every case, and from its 

 position, and that of the surrounding cells, was unmistakably 

 the single initial cell. It is usually quite regularly oblong, 

 and the divisions of the segments show a very considerable 

 degree of regularity. In no case was a regular three-sided 

 apical cell met with, although in one section (fig. 7) it was 

 nearly of this form; but an examination of the adjacent seg- 

 ments showed that this was in all probability only temporary, 

 as the youngest set of segments formed a nearly perfect 

 rectangle, and the three-sided form of the apical cell appar- 

 ently arose from the walls cutting off segments on opposite 

 sides of the cell deviating so far from their normally parallel 

 direction as to intersect. 



Sometimes the arrangement of the cells seen in longitudinal 

 section is almost as regular as in the Polypodiacea? or Equi- 

 setum (fig. 4), and in such cases the limits of the segments 

 are traceable for a long time; and in transverse sections this 

 is also evident for the first complete set of segments (fig. 6). 

 From a study of both, the successive divisions in the young 

 segments may be plainly determined. While not as dia- 

 gramatically regular as in the true leptosporangiate ferns, 

 nevertheless the divisions are much more definite than in 

 either O. regalis or O. cinnamomea, and except for the 

 irregularity in the formation of the root-cap, correspond very 

 closely to the regular fern-type. The primary tissue-systems 

 are better differentiated, and the plerome-cvlinder may be 

 tra ced back with certainty, at least in such regular forms as 



1 L. c. , pi. xx. 





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