928 REPORT—1899, 
4. The Maiden-hair Tree (Ginkgo biloba, Z.). 
By A. C. Sewarp, £.2.S., and Miss J. Gowan. 
The chief points dealt with in this paper may be summarised as follows :— 
1. Ginkgo biloba.—The history of our knowledge of Ginkgo; its external 
features and peculiarities; the variability in form and structure of the leaves; the 
structure and morphology of the male and female flowers; pollination and fertilisa- 
tion of the ovule; the development and structure of the embryo; the anatomy of 
the seedling and adult plant; comparison of Ginkgo with other genera, and its 
place in the plant-kingdom, 
2. Fossil Ginkgoacee.—A. general consideration of the evidence available 
towards an account of the past history of Ginkgo and closely allied plants; a com- 
parison of Ginkgo with various fossil types from Paleozoic, Mesozoic, and Tertiary 
horizons; the geographical distribution of Ginkgo during the Mesozoic and 
Tertiary epochs. 
5. Stem-structure in Schizeacez, Gleicheniacexe, and Hymenophyllacee. 
By L. A. Boopte. 
There is a wide difference between the types of stem-structure shown by the 
different members of the Schizeacee. Thus Lygodium has a stele in which the 
xylem forms a solid mass in the centre of the stem, and is surrounded by a con- 
tinuous ring of phloem pericycle and endodermis. 
Aneimia Phyllitidis, on the other hand, has a ring of separate bundles (or 
steles), which may be compared with those of Aspidiwm or other Polypodiacee ; 
each of them consisting of a band of xylem surrounded by a phloem, pericycle, 
and endodermis of its opvn. 
Mohria resembles Aneimia Phyllitidis in type. Certain species of Aneimia, e.g. 
A. mexicana, have in the internodes a complete ring of xylem bounded on the 
inner and outer side by a ring of phloem, pericycle, and endodermis, with a central 
pith, and thus resemble Marsila. Schizea has a ring of xylem surrounding a 
central pith, but no internal phloem or endodermis. 
The above four genera, which male up the Schizeacee, agree in having a 
stem-protoxylem, which is not well marked, as it consists of elements which are 
not annular or spiral, and are usually not specially small. Lygodium, Aneimia, 
and Mohria are exarch; in Schizea, however, the relative position of the proto- 
xylem has not been made out with certainty. 
In their main points the types of stem-structure found in the Schizeacce 
agree with the structures shown at successive levels in the stem of a ‘seedling ” 
plant of Polypodium, i.e. at successive stages in the ontogeny of such a fern. 
Hence the Aneimia type (which corresponds with that of a mature Polypodium) 
may be regarded as the more specialised type among the Schizeacee, and Lygodium 
(which corresponds in structure with the base of the stem of Polypodium) as the 
more primitive type. 
The Gileicheniacee and Hymenophyllacee also include forms with a solid 
central mass of xylem, but differing in some details from Lygyodium. The proto- 
xylem is well marked and composed of annular and spiral elements in both orders. 
Gleichenia is mesarch and closely resembles the fossil genus Heterangium. 
In the Gleicheniacee the only advance on the Lygodiwm type is found in 
Platyzoma (a subgenus of Gileichenia) in which there is a ring of xylem surround- 
ing a central pith, as in Schizea, but differing from the latter plant in having an 
inner endodermis. 
In the larger species of Trichomanes there is a solid xylem-mass, but with a 
group of parenchyma in connection with the one or two protoxylems, which are 
more or less centrally placed. In Hymenophyllum the corresponding parenchy- 
matous mass is large in proportion to the amount of xylem. In the smallest 
species of Trichomanes the stele of the rhizome takes the form of a collateral 
