AN ANATOMICAL STUDY OF GYMNOSPORANGIUM GALLS 409 
extends off on the lower side, is less regular, and soon breaks up into 
irregularly running strands of tracheids. The only parts which 
preserve a transverse stem structure are to the right and left of the 
center of the figure. There are a few wedges of xylem here which are 
separated by rays which are sometimes broader at the inner ends of 
the wedges. There are strands of tracheids running away from the 
central portion which are much bent and twisted. They extend in 
various directions. Some of them have tissue similar to the secondary 
bark of a normal stem, so they probably represent branches from the 
main central stem of the gall, but very much distorted and broken up. 
The tracheids which compose the irregular strands of vascular tissue 
usually have scalariform pits in their walls. The thickenings between 
the pits are often so slender as to give the appearance of spiral tracheids. 
In addition to the irregular strands of tracheids that have just 
been mentioned, peculiar stem-like structures occur in the gall. These 
often present a true transverse stem structure so there can be no 
mistake about their being stems. As the origin of these is better 
shown in the next species to be considered, they will be taken up in 
that connection. Two of these are shown at s, in figs. 4 and 5. They 
are much more irregular in structure here than is often the case. 
By further breaking up of the central cylinder deeper in the gall, 
a condition is finally reached in which there is nothing left but irregu- 
larly running strands of fibrovascular tissue. This condition is shown 
rather diagrammatically in fig. 5. All semblance of a transverse 
stem structure has disappeared, except towards the lower left side 
of the figure, and in two small areas in other places. The strands 
have become so twisted, in the central part of the figure, that the 
modified secondary bark tissue Hes towards the center. Strands of 
tracheids sometimes surround rather broad ray-like masses of paren- 
chyma as is shown in the upper part of the figure. From the central 
body, as figured, strands of tracheids radiate outward towards the 
peripher}^ of the gall. 
Sanford (8) makes the statement that there is but little distinction 
between xylem and phloem in the smaller bundles of the gall. The 
tracheids in the smaller bundles often show less lignification than 
those of the larger bundles, so that it is often difficult to differentiate 
sharply the tissues by staining. It is usually possible by careful 
staining, however, to show that certain of the cells are slightly ligni- 
fied and have scalariform pits in their walls. Furthermore, elongated 
