24 ART. 14— K. YEXDO: 



These zones as a whole does not form the genicnlum ; but some 

 of the zones, at both ends, share only partly. The zones of the 

 periclinal cells, as has been already remarked, are concentric arcs, convex 

 toward the apex of the frond. The boundaries of the geniculum, on 

 the contrary, are very often convex toward the base. The consequence 

 is that some of the zones partly share the geniculum (figg. 5-6). 

 This fact has been formerly noticed by the writer in his paper " Cor. 

 verse Japon." (PI. 1. fig. 21). 



The genicula of Amp. stelligera and its allies are also constructed 

 with a number of zones. Differing from the other multizonal genicula, 

 the critical part between the articular and the genicular portion is 

 much like the case of the unizonal genicula ; that is the ultimate ends 

 of the distal genicular cells are differentiated into peculiar parts, 

 corresponding, though not sharply, to the extragenicular portions of 

 the unizonal genicula. 



The staining material act upon the genicular cells in a similar 

 manner as in the case of the unizonal geniculum. Hence we may 

 easily point out the genicular portions with the naked eye when we 

 stain the frond in tola after decalcification. In the apical portion of 

 the fronds where the genicula have not yet been completely built up, 

 we can tell exactly the future genicula by this method, cf. Cor. verse 

 Japon. Explanation of PI. 1. fig. 21. 



The cellwall of the genicular portion proper consists of the four 

 lamella' as in the case of unizonal genicular cells. The tertiary 

 lamella, however, is sometimes very hard to detect. Almost all the 

 members which belong to this category have the bordered pits in the 

 lateral sides of the cells, besides the connecting pits at the distal ends 

 of the periclinal cells. These bordered pits are not perforations 

 between the cells but are septed by thin membranes of the middle 

 lamella. They are, as a rule, in rows parallel to the zones and are 



