1911] CHARLES—ANATOMY OF MARATTIA 83 
of Danaea and one specimen of Marattia fraxinea, all of which had 
reached the stage of an amphiphloic siphonostele with a medullary 
strand. He found a tendency of internal phloeoterma to degen- 
erate, and lists the Marattiaceae with pteridophytes that have de- 
veloped endarch collateral bundles. He gives no description or 
figures of the stele in this stage. 
It is evident that there is a fundamental difference in the transi- 
tion from protostele to solenostele in Angiopteris and Danaea, 
that there are other important points in the various accounts that 
do not harmonize, and that M arattia has been examined only 
incidentally from a few specimens. It seemed desirable, therefore, 
to make a thorough study of a large number of sporelings of Marat- 
tia in all stages of development. 
Material 
A very generous supply of sporelings of Maraitia alata of various 
ages was sent from Xalapa, Mexico, in November 1908 by Professor 
Barnes and Dr. LAnp, who described to me the places in which the 
young sporelings were found. The most favorable locations were on 
the east slopes of the mountains near Xalapa, at an altitude of about 
1140 meters, the temperature averaging about 30 C. The rainfall 
is 250 cm. per year, and although it is not evenly distributed, the 
moisture supply is sufficient to support a dense tropical rainy 
forest. In some places the upper vegetation had to be cut away 
to allow enough light to reach the ground to see the sporelings and 
prothallia. The most abundant supply of sporelings grew on the 
steep bank of a mountain torrent, in a soil composed of volcanic 
ash and yellow clay. Many of the youngest plants grew under the 
shelves made by the washing down of the surface; in one spot they 
grew just out of reach of the spray from a waterfall. 
The prothallium may persist until the sporeling has five or six 
leaves, or the sporeling may become independent when its primary 
root is only a few millimeters long. The smallest sporeling, 
illustrated in fig. 4, had a primary root about 4 mm. long, and a 
cotyledon of the same length, whose blade was just forked. As the 
leaf grows older, the veins dichotomize further, and the cotyledon 
becomes spatulate. The first four or five leaves are of this type, 
