654 SUMMARY OF CURRENT RESEARCHES RELATING TO 
tion of the testa of the seed the nucleus of the anatropous ovule takes 
part, as well as the two integuments. The mucilaginous layer is the 
epiderm, the power of swelling residing chiefly in the elongated hairs 
or sacs which spring from the inner side of the cuticle. These hairs 
have often a very delicate flagel attached to their apex, and they escape 
from the cells in which they are formed by the raising up in the form 
of a lid of the portion of the cell-w T all to which they are attached. 
Their function is to fix the germinating seed firmly in the soil. 
Achenes and Seedlings of Composite.* — Mr. W. W. Rowlee de- 
scribes the peculiarities of the achene and seed, and of the mode of ger- 
mination, in the case of a large number of American Composite. The 
proportion of the apparently good seeds which germinate varies greatly 
in the different species ; it is often very small, largest in the most 
abundant species. 
Biology of the Pericarp.f — Referring to the fact of the necessity of 
a free access of air to seeds during the period which intervenes between 
their maturity and their germination in order to maintain them in an 
active condition, Prof. A. Borzi describes the mode in which this is 
effected in the structure of the pericarp of a number of fruits, especially 
those of Leguminosse. A very good example is furnished by the 
legumes of Phaseolus Caracalla , the seeds of which maintain their power 
of germination for as long a period as five years. The aeration of the 
seeds is here effected by two minute apertures in the ventral suture. 
Similar contrivances are presented by many other Papilionacese. In the 
ripe drupe of the cherry and plum, access of air to the kernel is pro- 
vided by the disappearance of the vascular bundle wdffch before maturity 
connects the ovule with its placenta ; its place is supplied by a sub- 
stance which absorbs water with great avidity. 
Structure of Runners and Stolons. :J — Herr A. 0. Noelle describes 
in detail the peculiarities of structure of runners and stolons, both 
underground and aerial. In underground stolons the formation of hairs 
and of stomates disaj>pears altogether, and the epiderm is more or less 
replaced by a layer of cork. The hypoderm becomes collenchymatous ; 
the cortical parenchyme is more strongly developed ; the vascular- 
bundle-system occupies a more central position than in aerial stems, 
tending towards the formation of a closed cylinder. The development 
of pith is, on the other hand, greatly reduced. 
Cotyledons of Tropseolum.§ — Herr A. Winkler points out that the 
pair of leaves which first emerge above the soil in the germination of 
Tropseolum majus are not, as has usually been described, the cotyledons. 
These remain buried in the earth. The first pair of leaves are opposite 
to one another and alternate with the cotyledons. In several other plants 
it is also the case that the first pair of leaves are opposite, while the 
subsequent ones are arranged spirally. The mode of germination is 
similar in T. minus , peregrinum , tricolor , and brachyceras , and probably in 
all other species of Tropseolum. 
* Journ. Torrey Bot. Club, xx. (1893) pp. 1-17 (5 pis.). 
f Malpighia, vii. (1893) pp. 3-14. 
X ‘ Beitr. z. vergleichend anat. I nters, d. Auslaufer,’ Freiburg-i.-B., 1892, 72 pp. 
See Bot. Centralbl., 1893, Beih., p. 94. 
§ Abhandl. Bot. Ver. Prov. Brandenburg, 1892, pp. GO-2. 
