198 A Note on Vascular Tissue. 
view. The disappearance of a differentiated endodermis in the 
older parts of a phanerogamic seedling with secondary thickening 
is perhaps to be expected, if, as may be the case, it functions as a 
means of cutting off the actively conducting tissues from the paren¬ 
chyma. In the older regions, in which secondary thickening has set 
in, the directly functional conducting tissues may be cut off from 
the parenchyma by the now non-functional tissues of earlier 
d evelopment. 
A striking fact, which has perhaps some bearing on the question, 
is the general association of the endodermis with the phloem. In 
ferns it is present around the phloem of the protostele. Then 
phloem appears in the centre of the xylem strand, and concurrently 
with the appearance of parenchyma within this an endodermis cuts 
it off from the internal phloem. 
In the seedlings of Livistona Mauritania and Phoenix-dactylifera 
the bundles in the cotyledon-sheath are in certain regions associated 
with a cuticularized sheath of endodermis-like appearance. In many 
cases this is best developed in, and may be limited to the phloem 
portion of the bundle, being wanting on the internal face of the 
xylem. 
Without in any way admitting an adherence to the statolith 
theory, it is interesting to note that the endodermis is the region of 
statoliths in many plants, and that it is only with the younger 
regions that the tropistic power is usually associated. The fact 
that starch grains are often present in the endodermis after com¬ 
plete depletion of other regions may possibly be associated with the 
peculiarity of the cell walls. 
1 Boodle. I. Comparative Anat. of the Hymenophyllaceae , Schi- 
zaeaceae, and Gleicheniaceae. II. The Schizaeaceae. 
Ann. Bot. XV. 
2 Boodle, Ibid. III. The Gleicheniaceae. Ann. Bot. XV. 
3 Boodle. Further observations on Schizaeaceae. Ann. Bot. XVII. 
4 Boodle. “ The Anatomy of the Roots of Palms.” New Phytolo- 
gist, 1905. 
5 Chandler. On the Arrangement of the Vascular Strands in the 
“Seedlings” of certain Leptosporangiate Ferns. 
Ann. Bot. XIX. 
6 Drabble. The Anatomy of the Roots of Palms. Trans. Linn. Soc. 
1904-05. 
7 Farmer and Hill. On the Arrangement of Vascular Strands in 
Angiopteris evecta. Ann. Bot. XVI. 
8 Faull. The Anatomy of the Osmundaceae. Bot. Gazette, XXXII. 
9 Jeffrey. Trans. Brit. Assoc., 1897. 
10 Jeffrey. Morphology of the Central Cylinder of Angiosperms. 
Trans. Canadian Institute, 1900. 
11 Jeffrey. Structure and Development of the Stem in the Pleridophytes 
and Gymnosperms. Phil. Trans., Ser. B., Vol. 
CXCV., 1902. 
12 Schoute. Die Steliir-Theorie. Groningen, 1902. 
R. HADLEY, PRINTER, WHITFIELD STREET, LONDON, W. 
