A STUDY OF THE GEXICULA OF CORALLINiE. Q 



at righl angles to thai of the next order. The consequence is that 

 the dichotomy of one order comes in the plane at right angles to thai 

 of the adjacent one. This mode of dichotomy is -what I called 

 " decussato-dichotomy." (tig. H). 



A peculiar mode of bifurcation is found in the main stems of 

 Amp. aspergillum. In this species the articuli of the main stems are 

 as broad as their length and strongly compressed except those at the 

 basal portion. A few of the successive articuli below a bifurcating 

 articulus are much more complanated and have a longitudinal groove 

 along the meridional line, as if the tendency of the bifurcation at the 

 upper articulus were already indicated in the lower articuli. 



When several unequal genicula have been formed at the distal 

 end of an articulus, the branching mode becomes much more complex. 

 In the pinnated fronds, the two minor genicula are on both sides of 

 the middle one ; and when several minor ones are around the axial 

 one, the mode is whorly. In either case the middle and large one 

 is situated in the direction of the rachis and is always at the center of 

 the distal area. 



Strictly speaking, the size and the position of the genicula at the 

 distal end of an articulus from which the trichotomy and the pinnation 

 begin are different. In the trichotomy three genicula, equal in size 

 and in value, start at the end of an articulus from the same level. In 

 the pinnated branchlets, the two genicula on both sides of the axial 

 "•eniculum are much smaller than the latter. The genicular cells of 

 the axial one start from the zone lower by one than that of the 

 genicular cells of the pinnules (fig. 3). This was actually observed in 

 Amp. aberrans, Cor. officinalis, Cheilosporum maximum, etc. (cf. fig. 11, 

 Plate 1. Cor. vera 1 Japon.). 



The genicular cells have no power to develop into articular cells 

 by division or elongation. They are always transformed from the 



