244 
J. L. WEIMER 
modification. Stewart (1915) decided that the gall bundles are derived 
from the central cylinder entirely separate from and above the leaf- 
trace bundle. He illustrates this in Figure i of his paper, where he 
shows at K a section of an axillary bud from which he states the cedar 
apple is formed. The writer 'has in only one case found a structure 
similar to that represented by Stewart. In this case (PI. XV, Fig. ib) 
the structure in question is a section of one side of a terminal bud. 
An examination of all the sections in the series reveals the presence of 
the embryonic leaves. The young gall (g) beside this bud shows dis- 
tinctly the difference in the appearance of a true gall and a bud. 
Evidently Stewart has mistaken a normal axillary bud for a young 
gall. The writer was permitted to examine some of Stewart's slides 
and this convinced him that Stewart was mistaken in thinking these 
structures to be young galls. A careful search of these slides failed to 
reveal the presence of mycelium in the buds. Stewart admits that 
" the fungus has not entered the stem at this stage," but concludes that 
these axillary buds are young galls because structurally these two seem 
to him alike. So far as seen by the writer this worker's sections show 
no cases which, when carefully interpreted, as discussed below, demon- 
strate the axial nature of the gall. 
The excrescence caused by G. Juniperi-virginianae in its earliest 
stages consists simply of a few large parenchyma cells similar to those 
of the leaf. Often no distinct epidermal tissue is apparent at this 
stage but before the galls enter the winter condition a few layers of 
cork cells are laid down. The time at which this exterior covering is 
formed varies in different galls. The beginning of such a layer of cork 
cells is evident in some very young stages while in other cases galls 
nearly mature show almost no sign of its development. 
That the fibro-vascular system of the gall originates from that of 
the leaf is evident from the study of the very young stages. How this 
takes place may be seen in Plate XHI, Figures i and 2. The leaf-trace 
bundle first shows an increase in size beneath the enlarged portion of 
the leaf. Soon strands of vascular tissue are found leaving the leaf 
bundle at almost an angle of ninety degrees and passing into the young 
gall. The vascular tissue of the gall develops rapidly and very early 
in the development there is present a large amount of conductive tissue 
in the gall. This same method of origin of the vascular tissue of the 
gall can be traced in those growths which occur near the base of the 
leaf. In this case, however, the leaf-trace bundle is very materially 
