6 
2. The first secondary pinnula is the acroscopic, i. e. that directed toward the 
apex of the leaf; the arrangement is anadromous, the lamina polystichoid 
This difference in the sequence of the secondary pinnules, which, as a rule, is re- 
peated in the later divisions of the leaf, may appear to be rather unimportant, but 
it stands in correlation to the different development of the acroscopic and basisco- 
Fig. 1. reseed structure. Fig. 2. Anadromous structure. 
pic pinnules; the most developed pinnules claim the largest room. In the basal 
pinne there is downward room enough for the extremest development of the 
secondary basiscopic pinnules, and a wider space is obtained for the first basiscopic 
— when it removes as number two on the midrib of the pinna, by which 
: n the interior tertiary pinnules also get room for a greater development. In 
i all more divided species the arrangement of the secondary pinnules of the basal 
= Larne is anadromous. In the middle of the leaf, where there is less room, it is 
os othe In a series of species the two basal secondary pinnulz are about equally 
ae developed and about of the same size as the following ones, their midribs run out 
- from the midrib of the pinna from nearly the same point, the pinnules being 
2 a but more oe staid the basiscopic is the first, a little closer to the paras 
. 
1 
a ee a eee 
