1922] BLOMQUIST—ANGIOPTERIS 185 
The next point to be observed is the appearance of the stem tip. 
About the time the first leaf has emerged from the gametophyte, 
a slight depression is seen on the dorsal side of the petiole where 
this passes into the root. At the bottom of this depression there 
is a well defined apical cell, which can easily be seen from longitu- 
dinal sections of the young sporophyte. The second leaf appears 
on the crest of this depression, usually about 130° from the first, 
while the corresponding root emerges directly below, next to the 
primary root. The succeeding leaves appear at approximately 
the same distance from the next older leaf that the second appeared 
from the first, thus forming a spiral arrangement which may be 
clockwise in one plant and counter-clockwise in another. This 
habit has an important bearing upon the development of the internal 
structure, as will be shown later. The succeeding roots grow through 
the cortex and appear from below the thickening stem, and later 
penetrate the sides. The relation between the roots and the 
corresponding leaves cannot be determined from external appear- 
ances after the third and fourth leaves have appeared. In none of 
the specimens studied had the roots branched, and no differences, 
except in size, could be discerned from the external appearances of 
the different roots. 
A characteristic feature of the mature plants of the Marattiaceae 
is the presence of conspicuous fleshy stipules. In the first leaf 
of Angiopteris no stipules are visible, while in the second slight 
thickenings show their rudiments. No well developed stipules 
appear until the fourth leaf. At this stage the stipules appear as 
lateral swellings on the petiole as soon as the leaf is visible. As 
the leaf develops and the petiole elongates, the upper part of the 
stipule splits away from the petiole, and this gives rise to the more 
or less pointed lobes. In all sporelings examined there were no in- 
dications of dorsiventrality, either in external appearance or internal 
structure. 
GENERAL INTERNAL STRUCTURE 
The general internal structure of a stem of Angiopteris which 
has developed beyond the first few stages may be divided into two 
main regions, the cortical and the central vascular. The cortex, 
