* 
1911] TUPPER—GINKGO BILOBA 375 
their distribution. PENHALLOW,’ GopPERT,’ and others have de- 
scribed the existence of crystal cells, or idioblasts, in the branch 
of Ginkgo, and PENHALLOw has even added that they occur scattered 
throughout the wood and often in vertical series. 
From a careful examination of the root, I have found that these 
idioblasts, or crystal-containing cells, and parenchyma cells invari- 
ably occur in longitudinal rows, or series, which run from ray to 
tay. In every single case these parenchyma and crystal cells were 
found in relation with a ray, as is shown in figs. 1, 2, and 3. 
Fig. 1 is a radial section of the wood of the root, and shows the 
large, round, crystal cells, or idioblasts, in a longitudinal row con- 
hecting two rays. To the side of and intermingled with the crystal 
cells of this row are parenchyma cells, some of which appear as 
appendages of the rays. These parenchyma cells apparently give 
rise to the crystal cells, or else are modified into them. Some of 
the crystal cells are torn, due to the fact that the crystals of calcium 
oxalate which they contained were not fully dissolved by treating 
with hydrofluoric acid. The crystal cells are seen in contact with 
a ray in a tangential view in fig. 3. 
The Ginkgoales are the connecting link between the Archi- 
and Metagymnospermae, possessing, as they do, motile sperm 
cells and other reproductive characters of the Archigymnospermae, 
together with anatomical characteristics of the Metagymnospermae, 
such as clearly marked annual rings, bars of Sanio, opposite pits 
on their tracheids, and only vestigial traces of centripetal wood 
(in their foliar organs). The wood parenchyma, however, is related 
to the rays, and extends in radial rows, unlike the tangentially 
distributed wood parenchyma found in the conifers. Wood 
parenchyma, like annual rings, appears to have been produced 
by woody plants as a reaction to the arrival of winter conditions 
in the geological and climatic evolution of the earth. Figs. 2 and 
4, the former a radial, the latter a transverse section of the Ginkgo 
Toot, also show the peculiar distribution of the xylem parenchyma 
and crystal cells. 
Like the Pineae, probably the oldest conifers, Ginkgo has its 
3 PENHALLOw, D.P., A manual of the North American gymnosperms. p. 209. 1907. 
*Goppert, H. R., Monographie der Fossilen Coniferen. p. 266. 1850. 
