174 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
27 types, arranged in six groups, three of these belonging to aquatic or 
marsh plants, and three to terrestrial plants. The first group includes 
the submerged leaves of aquatic plants, of the Vallisneria, Myriophyllum , 
and Isoetes types ; the second, floating leaves of the Nymphsea type ; the 
third, leaves of bog-plants adapted to an aquatic life, of the “flooded” 
and Arum types. The fourth group comprises those which present 
adaptations for the promotion or checking of transpiration, xerophytes, 
halophytes, &c. ; the fifth, those provided with mechanical or chemical 
protections against consumption by animals, or with contrivances for the 
capture of insects ; the sixth group embraces the scale-leaves of parasites, 
epiphytes, and saprophytes, of the Lathrsea and Viscum types. 
Special Adaptation of Leaves.* * * § — Prof. P. Czapek notes that in 
Cirsium eriophorum , when growing in sunny localities, the leaves have 
two rows of comb-like pinnae which stand erect ; while when growing in 
the shade, all the pinnse are expanded flat. We have here an evident 
adaptation to different degrees of illumination. 
Leaves of Cecropia.f — The leaves of Cecropia have hitherto been but 
imperfectly described, owing to their enormous size. According to Herr 
A. Richter, they are characterised by large intercellular spaces, which 
are grouped in the hypodermal parenchyme of the larger veins which 
project on the under side of the leaf, round the vascular bundles. Ho 
latex-tubes containing caoutchouk could be detected. 
Pearly Glands of the Vine.t — M. J. Dufour gives an anatomical 
account of these structures, which appear especially on the young shoots 
of the vine in spring. They contain an oil, which increases in quantity 
with the age of the gland, and are probably organs of secretion. 
Nature and Origin of Stipules.§ — From a study of the stipules in 
a large number of Monocotyledons and Dicotyledons, Mr. A. A. Tyler 
has come to the following general conclusions. 
The sheathing petiole has its origin independently of the true petiole, 
and is formed by a concomitant development of the lateral and central- 
basal portions of the primitive leaf. The ligule (Graminese, &c.) is a 
special development of the apical parts of the lateral portions of the 
primitive leaf along the ridge between the sheathing petiole and the 
distal parts of the leaf. The ochrea (Polygonacese) is related to the 
ligule, and is generally associated with the sheathing petiole. It con- 
sists of the apical tissues developed in those cases where the sheathing 
petiole completely surrounds the stem, or did so in the ancestral con- 
dition. The lateral portions of the primitive leaf, when separated in 
greater or less degree, constitute stipules in the usual acceptation of the 
term ; but they may be variously modified by subsequent evolutionary 
changes. The lateral portions of the primitive leaf represent poten- 
tially the ligule, the ochrea, and the margin of sheathing petioles and 
stipules ; but they are often incorporated with the other portions as the 
wings of petioles, and as lateral basal portions of leaf-blades. 
* Oesterr. Bot. Zeitschr., xlviii. (1898) pp. 369-71 (1 fig ). 
t Biblioth. Bot., Heft 43, 1898, 25 pp. and 8 pis. 
j Arch. Sci. Phys. et Nat., vi. (1898) p. 647. 
§ Ann. N.Y. Acad. Sci., x. (1898) pp. 1-49 (3 pis.). Cf. this Journal, 1895, 
p. 653. 
