132 RELATION OF PHYLLOTAXIS TO MECHANICAL LAWS. 



is of special interest in connection with renewed growths. Both 

 phenomena again may be involved in the general rise of phyllo- 

 taxis observed in young plants which develop mature axes with a 

 comparatively high ratio of curves. 



Thus it is clear that the youngest plants of Aspidium, Filix-Mas* 



Fig. 52. — Saxifraga wmbrosa, L. Section of perennating foliage-shoot (January) : 

 (24-3) system of previous year enclosing (3 + 5) system of the new season's 

 growth : the latter separated by a dotted line. 



or first-year seedlings of Nymphaea, do not possess the (5 + 8) 

 system of the adult (c/. fig. 94). 



The transition may take place at the commencement of a new 

 season's growth as in Saxifraga umbrosa, or new curves may be 

 added from time to time, as in the inflorescence of Bipsacus, to 



* De Bary, Comparative Anatomy, p. 285. 



