188 BOTANICAL GAZETTE [MARCH 
It is evident that by a continual loss of tissue from one edge and 
an addition on the other, in the successive sections, the crescents 
will appear to move in a circle, indicating that the strand is a more 
or less open spiral. The explanation for this spiral condition is to 
be found in the spiral succession of the leaves. In the stages above 
the eighth leaf, a medullary strand appears on the inner side of the 
central strand, usually slightly above and opposite the junction 
of a root stele. This passes diagonally upward, crosses the central 
parenchyma tissue, and fuses with the commissural strand before 
the latter has joined the central strand (fig. 5). In this condition 
they meet the edge of the central strand, and the commissural 
strand fuses with the latter and is lost. The medullary strand, 
fused to the inner side of the central strand, but retaining its 
identity, passes upward until the union of the root and the central 
strand has been cleared, when it frees itself and repeats its course 
across the central parenchyma tissue. This behavior of the 
medullary strand agrees in the main with the condition in Marattia 
as described by Miss CHARLEs (7). In the lower levels of the stem 
a mucilage canal appears in the center of the parenchyma tissue. 
This canal divides wherever a leaf trace is given off, and one of 
the branches follows the inner side of the latter. 
Each leaf trace is definitely related to one root. HOoLtE (10) 
has reported the same condition in Marattia, but found two roots 
to each leaf in Angiopteris. The writer in some cases found two 
roots attached on the same level, and it appeared as if two roots 
were related to one leaf. After following out the series, however, 
it was found that these roots were related to different leaves. 
This variation will be discussed more fully later. The root which 
appears almost opposite each leaf trace is related to the next leaf 
above. In the younger stages each leaf trace is joined to the 
central strand directly above the insertion of its corresponding 
root (fig. 9); but in the older stages the leaf trace may be displaced 
to the right or left of the corresponding root, as the case may be, 
due to the spiral condition of the central strand (figs. 11-15). 
The distance between the root stele and the junction of the corre- 
sponding leaf trace above increases also in the successive stages. 
