On the Seedling Structure of Gymnosperms. III. 
BY 
T. G. HILL, F.L.S., 
University of London ; University and Goldsmiths Colleges ; 
AND 
E. de FRAINE, F.L.S. 
University of London ; Goldsmiths' College . 
With Plate XXX, and four Figures in the Text. 
GINKGOACEAE. 
Ginkgo biloba. 
HE appearance of the seedling of this plant, and the germination 
A of the seed, have already been described and figured by Sprecher, 2 
and are sufficiently well known to render an extended description unneces- 
sary. Figs. 1-3, PL XXX will suffice to recall its more obvious features : 
the cotyledons usually are two in number but three sometimes occur 
(Fig. 3, PL XXX), a fact already recorded by Lyon 1 and Sprecher. 2 
The seed-leaves are frequently unequal in length ; they exhibit a more 
or less well-marked lobing, and throughout their existence, remain em- 
bedded within the seed where they are closely adpressed by their ventral 
surfaces. These facts have already been remarked upon by Strasburger, 3 
Worsdell, 4 and Seward and Gowan. 5 According to Lyon 6 the seed-leaves 
are normally equal and entire. Towards the basal region the cotyledons 
separate in the manner indicated in Fig. 2, PL XXX. Although the 
details of the histology of the seed-leaves have been investigated by other 
authors, more especially by Sprecher, 7 it will not be out of place to draw 
1 Lyon : Embryogeny of Ginkgo (Minnesota Bot. Studies, 1904). 
2 Sprecher : Le Ginkgo biloba (Geneve, 1907). 
3 Strasburger : Die Coniferen und die Gnetaceen (Jena, 1872). 
4 Worsdell : On Transfusion Tissue : its Origin and Function in the Leaves of Gymnospermous 
Plants. (Trans. Linn. Soc. Lond. ; Bot., 2nd Ser., v.) 
5 Seward and Gowan : The Maidenhair Tree ( Ginkgo biloba). (Ann. Bot. xiv, 1900.) 
6 loc. cit. 7 loc. cit. 
[Annals of Botany, Vol. XXIII. No. XCI. July, 1909.] 
