40 A.RT. U-K. YENDO: 



openings septated or non-septated, are always met in the cells of the 

 Diclyotale, the Floriàeœ and many of the Phceophyccce and some of the 

 Chîorophyceœ. 



I have already mentioned in connection with Amp. dilatala (p. 

 25) that the cell contents in the surrounding cells of the geniculum 

 are consumed. This may possibly always be the case in the other 

 members. The cell contents are in greater part FJoridese starch. 

 There is little doubt that the starch is transformed into a soluble 

 hydrocarbon and carried on through the thin membrane of the border- 

 ed pits to be consumed during the formation of the geniculum. 



The Value of the Geniculum as a 

 Systematic Character. 



The presence of the genicula has been counted as the crucial 

 point in distinguishing the Gorallinœ from the Melobesiœ. But little 

 heed has been given to the systematic value of the geniculum in the 

 study of the Coraîlinœ. The external shape of the articuli, which is 

 undoubtedly highly variable, has been the important specific charac- 

 ter ; and the position of the propagating organs played a weighty 

 rôle in the generic determination. The mere external appearance of 

 the genicula has sometimes been mentioned by writers in describing 

 the species. 



The internal structure of the genicula, however, has some 

 coincidence with the external morphological characters. SoLMS 

 remarked the différence between the genicula oîCorallina and Amphiroa 

 as noted before (p. 23). But we found many exam] »les which disprove 

 his observation : some of the species reckoned under the genus 

 Amphiroa have unizonal genicula, and some multizonal, as has been 



