ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
557 
gentian-violet, and eosin ; the saline solutions, lithium chloride, barium 
chloride, strontium nitrate, calcium nitrate, sodium chloride, and ferric 
chloride ; the first-named in each group giving the best results. In both 
herbaceous and woody dicotyledons the vascular bundles acted, in all 
the cases examined, as the sole conductors of soluble pigments, which 
never spread beyond them into the adjacent tissues. In woody species 
particular branches or parts of the plant appeared to be in connection, as 
far as the absorption of pigments is concerned, only with definite portions 
of the root. The saline solutions, on the other hand, after ascending 
through the vascular bundles, diffused themselves after a time through 
the adjacent tissues and finally through the whole plant. In the 
absorption of nutrient substances any particular part of the plant is not 
dependent on the activity of any special portion of the root, but rather 
on the entire accumulation of salts in the stem, which again is derived 
from the activity of the entire root. 
Excretion of Drops of Water from Leaves.* — Dr. A. Nestler states 
that, while the excretion of drops of water from the leaves of plants is 
often effected by special organs (hydathodes), this is not always the case. 
In Agapanthus umbellatus , which has neither epitheme nor water-pores, 
it takes place partly on the upper side of the leaf, partly on the under 
side of the apex. In grasses it may be brought about in various parts 
of the leaf. In Tradescantia viridis the exudation is effected through 
water-clefts placed in a row on the margin of the upper side, the only 
stomates on this side of the leaf. In Phaseolus multiflorus the club- 
shaped hairs do not appear to have this function. 
Aeration of the Stem of Mikania. j — Mr. W. W. Rowlee finds that 
the primary root of Mikania scandens gives rise to a great number of 
slender lateral roots, especially on the upper side, which grow towards 
the surface of the water of the marshes in which the plant flourishes. 
He regards these as aerotropic organs. When planted in dry soil, these 
roots appear as small erect knees, containing a large number of schizo- 
genous air-passages, which appear every year. 
(3) Irritability. 
Sleep of Plants.]; — Pursuing his investigation on the advantages 
afforded to plants by the nocturnal position of the leaf or leaflets, Herr 
E. Stahl finds, in a large number of plants examined, that it acts as a 
protection against the deposition of dew. The effect is to promote 
transpiration, and thus increase the amount of nutriment conveyed to 
the assimilating organs. He does not favour the view that the main 
object is a protection against excessive radiation. 
The nocturnal position of leaves or leaflets may be classed under two 
heads : — (1) They are directed downwards, so that the under side is 
better protected than the upper side against the deposition of dew (Bio- 
phylum sensitivum , Oxalis Acetosella , Bobinia pseudacacia , Hedysarum 
gyrans, Impatiens noli-tangere, &c.). (2) They are so placed that the 
* SB. K. Akad. Wiss. Wien, cv. (1896) pp. 521-50 (2 pis.). 
t Proc. Amer. Micr. Soc., xv. pp. 143-56 (6 pis ). See Bot. Centralbl., 1897, 
Beih.,p. 95. * 
X Bot. Ztg., lv. (1897) l te Abth., pp. 71-109. Cf. this Journal, 1895, p. 657. 
