ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
75 
Cryptogamia Vascularia. 
Development of Tissues in Vascular Cryptogams.* — M. G. Poirault 
has investigated the mode of development of the tissues in the vegetative 
organs of a number of Vascular Cryptogams, especially in the root, stem, 
and leaf. 
The segments which are cut off from the three-sided apical cell of 
the root, first divide by vertical walls ; horizontal walls appear only at 
a later period. The first wall is that in a nearly radial direction, called 
by Niigeli the sextant-wall, by De Bary and Van Tieghem the radial 
wall, which the author proposes to term the “ curved wall ” (cloison 
courbe). The two daughter-cells thus formed are of unlike form, one four- 
sided, the other three-sided. The two succeeding walls are parallel to 
the surface ; the outer one, which appears first, is called the “ cortical 
wall,” the other the “ pericyclic wall ” (Nageli’s cambium-wall). The 
entire segment now forms a layer composed of eight cells, of which the 
two inner ones are the initials of the central cylinder, the four outer 
ones of the cortical layer. A somewhat different mode of division occurs 
in Equisetum and Azolla. 
As regards the division in the stem, Salvinia, Marsilea, and Azolla 
grow by a two-sided apical cell (not three-sided, as stated by Hanstein 
in Marsilea), and their subsequent development shows great uniformity. 
The segments are arranged in two rows, and they all exhibit a bilateral 
symmetry. In Equisetum arvense there are always a tetrahedral apical 
cell and three rows of segments (not four rows, as described by 
Hofmeister). 
In the leaf the author found invariably a two-sided ajncal cell with 
two rows of segments. The first division-wall corresponds to that of a 
two-celled stem-segment. The original segment divides, by a com- 
plicated process, into an outer and an inner layer of secondary seg- 
ments ; these again divide parallel to the surface, and thus give birth to 
the initials of the various tissue-systems. 
Structure of Tmesipteris.t — Mr. A. V. Jennings and Miss K. M. 
Hall describe the more important points in the structure of Tmesipteris 
tannensis (including T. Forsteri and Billardieri ): — viz. those of the axis, 
including the fibrovascular system of the leaf and of the sporanges. The 
authors agree with Solms-Laubach, rather than with Eichler and Bertrand, 
in regarding the whole sporangiferous structure as a modified phyllome, 
rather than as a special sporangiferous branch. They find the protoplasm 
of the cells, especially those of the cortex, to be infested with the liyph® 
of an undetermined fungus, similar to that described by Treub and 
Bruchmann in species of Lycopodium. 
Muscineas. 
Starch in the Aquiferous Tissue of Mosses.J — Herr M. Dalrner 
finds the cells of the aquiferous tissue in the columel of the capsule of 
Mnium cuspidatum and other mosses, to be provided with chlorophyll- 
* Mem. Acad. Imp. Sci. St. Petersbourg, xxxvii. (1890) 26 pp. and 5 pis. See 
Bot. Centralbl., xlviii. (1891) p. 77. 
t Pmc. R. Irish Acad., ii. (1891) pp. 1-18 (5 pis.). Cf. this Journal, 1891, p. 499. 
X Flora, xlix. (1891) pp. 460-5. 
