670 



PROFESSOR F. O. BOWER ON 



Comparison may be made with the juvenile leaves of Todea superba, in which 

 species the mature leaves are dissected into fine lacinise, each containing a single 

 vascular strand. The terminal branchlets of the adult leaf or pinna show obvious 

 dichotomy, and the relation of the lacinise indicates a sympodial origin. The first 



b e 



Fig. 5. — Juvenile leaves of Todca barbara. ( x 4. ) 



a 



Fig. 6, a-c. — Cotyledons of Todea superba, showing different complexity of construction. ( x 3.) 



leaves appear in strong antithesis to those of Osmunda, for they have from the first 

 not only separate lacinise, but also sympodial development. This is shown in fig. 6, 

 a, b, c, which are readily understood. They are all cotyledons, and it appears that 

 with the narrow laciniae goes an early adoption of sympodial development. But none 

 the less dichotomous branching underlies the structure of the cotyledon, as it also 

 does that of the adult leaf. 



