ISOETES JAPONICA, A. BE. 



355 



emerge from the left half of the lobe are derived from the flank of another arm of the 

 rhizophore- stele (text-fig. 10). 



In text-fig. 13, which was prepared from the same specimen, the roots which cannot 

 be seen in a surface view of the actual specimen owing to the pronounced curvature of 



e edge of the lobe, are also included {cf. PL 33. fig. 6 ; PL 34. fig. 9). 



In the diagram represented in text-fig. 11, the series of roots hear numbers 



corre- 



iponding to those of text-fig. 13 ; hence the oldest 



hich always consists of 



Text-fis. 13. 



Isoetes japomca. Diagram showing the actual arrangement of the roots on one lobe of the caudex represented 



in text-fig. 12. The roots are nunabered as in text-fig. 11. 



single root, is number 1. This root occurs on the extreme edge of the lobe, and in 

 old specimens is invariably missing, since it is cut off together with the most peripheral 

 portion of the lobe as soon as decortication takes place. 



The theoretical arrangement of the roots, based upon the same specimen, is repre- 

 sented in text-fig. 14, in which all the roots of every series are shown. In this diagram 

 every root differentiated by the primary meristera is made to appear on the surface of 

 the caudex, whereas in text-fig. 13 only those roots which at that stage have actually 

 appeared on the surface are represented. It so happens that the nearer the long axis of 



