ZOOLOGY AND BOTANY, MIOEOSCOPY, ETC. 619 



entrance of an antherozoid into the central cell was observed. At an early- 

 period in the development of the embryo it consists of eight primary 

 cells, each of which has the form characteristic of the apical cell of the 

 mature stem and root. 



The vascular bundles of the stem contain no true vessels, but tracheids, 

 which are chiefly scalariform, though there are some spiral and reticulate 

 ones, and sieve-tubes. Each leaf originates from a single segment of 

 the apical cell of the stem. The leaf-stalk developes at first much more 

 rapidly than the lamina, which remains very small proportionately until 

 the latter part of the summer previous to its unfolding, after which its 

 development is remarkably rapid. As in some other ferns, the 

 arrangement of the leaves in the mature plant is in a 5/13 spiral 

 phyllotaxis, although they are so crowded that it is difficult to make this 

 out. The growing point of the stem is completely concealed by the 

 young leaves ; the epidermis of the stem is very feebly developed. 



The sori are formed in connection with the veins. The division of 

 the nucleus in the formation of the spores was very clearly followed out ; 

 the formation of the nuclear spindle was distinctly seen, but no satisfactory 

 view of the nuclear disc could be obtained. The cells of the annul us 

 soon project above the other cells of the sporangium, and their division- 

 walls become thicker. The cells of the annulus on one side of the 

 sporangium are rather more elongated than the others ; and four, or 

 sometimes only three of these near the base of the capsulfe form the 

 " stomium," at which place the capsule opens. 



Branching of the Frond of Ferns.* — According to Herr W. 

 Mohring, sympodial branching in the frond of ferns never takes place in 

 any of the species examined by him. In the youngest state of the frond 

 he finds a two-edged apical cell, which soon produces a periclinal, and 

 then cuts off segments towards the upper and under side of the leaf. 

 This cell divides again by an anticlinal into two cells, the true apical 

 cells of the frond. Beneath the apex the segments are produced in 

 acropetal succession. The course of the veins is dichotomous, one of 

 the two branches having greater energy of growth than the other ; but 

 the branching of the leaf remains monopodial. Its growth in length is 

 determined only by the apical cell, its growth in breadth by the marginal 

 cells. 



Leaves of Polypodiacese.f — Herr W. Benze describes the adaptations 

 for different degrees of moisture in various Polypodiaceae. A typical 

 assimilating system is wanting in Adiantum ; palisade-cells occur in 

 species of AcrosticJmm, in JPlaty cerium alcicorne, and Polypodium Lingua ; 

 branching palisade-cells in As])lenium falcatum, Aspidium Sieboldi, 

 Bleclmum, Dicksonia, and Doodia. Stomata are found only on the under 

 side of the leaf, and depressed in the tissue only in Polypodium Lingua 

 and Platycerium alcicorne. The mechanical tissue is usually composed of 

 bast-cells, less often of coUenchymatous cells. 



Aspidol from Aspidium Filix-mas4 — Signer G. Daccomo has 

 obtained from the root of the male fern a compound which has received 



* Mohring, W., 'Ueb. d. Verzweigung cl. Farnwedel,' 33 pp., Berlin, 1887. See 

 Bot. Centralbl., xxxiv. (1888) p. 7. 



t Benze, W., ' Ueb. d. Anatomie der Blattorgane einiger Polypodiaceen,' 47 pp., 

 Berlin, 1887. 



X Ann. Cbiru. Farm., Ixxxviii. pp. 69-90. See Journ. Chem. Soc. Loud., 1S88, 

 Abstr., p. 521. 



