266 
Pr anker d. — On the Structure and Biology of 
Summary. 
1. The anatomy of the seedling is very simple. There is no trace of 
the * double bundle ’, and root structure is present in the hypocotyl. 
2 . The mature plant consists of subterranean, aquatic, and aerial 
portions, and exhibits considerable divergence of structure. H. palustris 
shows a trace of ‘ polystely ’ at the base of the inflorescence axis, and more 
or less perfect steles are formed from arcs of vascular tissue in the lateral 
inflorescence axes of H. inflata near their junction with the main stem. 
3. The plant is markedly sensitive to gravity, and the special develop- 
ment of statocyte tissue corresponds in time and position with the occurrence 
of graviperception. 
4. The roots show some peculiarities of position. 
Dr. Fritsch first suggested that I should undertake this work, which 
has been mainly carried out in Prof. F. W. Oliver’s laboratory, University 
College, London. I wish heartily to thank Dr. Coulter and his staff, 
particularly Dr. W. J. G. Land, for their kindness to me while working at 
Chicago University. My acknowledgements are also due to Dr. Agnes 
Arber for the kind and ready assistance she invariably afforded me. 
Literature cited. 
1. Boodle (’03) : On Descriptions of Vascular Structures. New Phytologist, vol. ii, p. 107. 
2. : Comparative Anatomy of the Hymenophyllaceae, Schizaeaceae, and Gleichenia- 
ceae. Annals of Botany, vol. xvii, p. 516, note. 
3. Brokschmidt, Otto (’04) : Morphologische, anatomische und biologische Untersuchungen 
liber Hottonici palustris. Inaugural-Dissertation, Friedrich-Alexander-Universitat. 
4. Darwin, F. (’04) : Presidential Address. Section K, British Association Report, p. 766, note 6. 
5. Gwynne-Vaughan (’97) : On Polystely in the Genus Primula. Annals of Botany, vol. xi. 
6. Jeffrey (’00) : The Morphology of the Central Cylinder in the Angiosperms. Trans. 
Canad. Inst., vol. vi, 1899. 
7. Kamienski (1878): Vergleichende Anatomie der Primulaceen. Abhandlung d. Naturforsch.- 
Ges. zu Halle, Bd. xiv. 
8. Schenk (1886) : Biologie der Wassergewachse, p. 13. 
9. Scott (1890) : On the Origin of Polystely in Dicotyledons. Annals of Botany, vol. v, p. 514. 
10. Solereder (’08): Systematic Anatomy of the Dicotyledons, vol. i. 
11. Stokey (’07) : The Roots of Lycopodium pithyoides. Botanical Gazette, vol. xliv. 
12. Tansley and Chick (’03) : On the Structure of Schizaea malaccana. Annals of Botany, vol. 
xvii, p. 498. 
13. Thomas (’04): Root Structure in the Central Cylinder of the Hypocotyl. New Phytologist, 
vol. iii, p. 104. 
14. (’07) : A Theory of the Double Leaf-trace founded on Seedling Structure. New 
Phytologist, vol. vi. 
