RENNERT: THE PHYLLODES OF OXYPOLIS FILIFORMIS 409 
rows of cells, the stomata occurred in definite rows separated from 
each other by five sterile epidermal rows. Hypoderm was absent. 
The chlorophyl-cells followed directly upon the epidermis. This 
tissue was reduced to about three rows, and the palisade character 
of the first row of cells was not very marked. The endoderm was 
also less developed. It consisted of only one to three rows of 
cells. The stellate tissue of the other form was entirely absent 
here. As a consequence of the meager development of endoderm 
the fibro-vascular bundles jutted out into the central cavity. The 
xylem in the bundles was reduced and the position of the resin 
duct changed. Inthe normal type it was always to be found out- 
side of the phloém; in these phyllodes it was on the other side of 
the bundle near the xylem. This position of the duct has been 
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Fic. 3. Partial cross-section of phyllode, hydrophytic form, 149. 
pointed out by Van Tieghem as more primitive or juvenile. The 
diaphragms were composed entirely of thin-walled cells and the 
anastomosing bundles contained in them were much weaker and, 
contrary to the habit in the solid phyllode, anastomosed as freely 
at the center of the septum as about the edge. No trace of glands 
in the phyllode have been found and there is consequently no 
general convergence of bundles toward any single point in the 
margin. 
The phyllodes of the submerged plants possessed in all cases 
the same structure as those grown under the bell-jar and exhibited 
an additional modification in their method of propagation. New 
plants were developed from the nodes of the xerophytic stems 
which had been developed before the plants were submerged and 
also in turn from the nodes of plants produced under water. 
The water in which the immersed plants were grown presented 
