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THE BOTANICAL MAGAZINE. 



[Vol. XXXV. No. 415. 



of typical form. The latter has a definite length so that it oc- 

 casionally overlaps each other in shorter internodes, thus indicating 

 a transitional type. Foliar arrangement can be estimated from that 

 of gaps, which are arranged in Ys counterclockwise manner.^^ 



Adiantum monochlamys Eat. External and internal construction 

 is similar to the preceding, but in this species the overlapping of 

 gaps is so frequent that it appears often like a dictyostelic type. 



Athyrium nipponicum (Mett.) Hance. Creeping rhizome with 

 foliar arrangement in Vs clockwise manner. A model of the stele 

 constructed from the serial sections (Pig. 1, A) and a figure developed 

 from it (Fig. 1, B) il- 

 lustrates the construc- 

 tion of the stele. Ac- 

 cording to these features 

 it may be seen that 

 there are three horizon- 

 tal rows of very long 

 gaps, and also that a 

 foliar trace departs from 

 the bottom of a gap 

 (Fig. 2, A; marked with 

 O) though it divides 

 immediately after the 

 departure. It is clear 

 that foliar traces and 



gaps arrange themselves in ^s clockwise manner. Then, the relation 

 of two consecutive gaps in one and the same row will be considered. 

 The end of a gap approaches the next one, so that two gaps are 

 separated by a short transverse commissure. This relation is in- 

 variable throughout the rhizome regardless of internodal length. In 

 such a way three or four gaps overlap in every cross section, so that 

 the stele is divided always into two or three meristeles. Exceptionally 

 a gap may be discrepant with the next (Fig. 1). Such a case 

 will be illustrated later in other species. 



Athyrium yokoscence (Fr. et Say.) Chr. Oblique rhizome with 

 leaves closely arranged in '/3 counterclockwise manner. This arrange- 

 ment affects the construction of ths stele, which is quite different 

 from the preceding species (Fig. 2, B). Behavior of foliar traces is 



Fig. I. Diagramatical model of stele of Athy- 

 rium nipponicum (A), and its developing figure (B). 



1) Direction of spiral foliar arrangement viewed from the apex. 



