594 Holden and Bexon .— The Seedling of Acer Pseudoplatanus . 
Summary. 
1. The development of the seedling vascular system of the sycamore, 
Acer Pseudoplatanus , is described from an early stage in its differentiation 
up to a period in which the epicotyl is beginning to assume a dominant role. 
2. It is held to illustrate an early stage in the evolution of diagonal 
root symmetry of which the stable tetrarch stage is shown by Calycanthus. 
3. An account is also given of the food reserves found in the embryo 
and young seedling. These include starch, a fatty substance, and at least 
two proteins, all of which are digested and utilized in the early stages of 
seedling growth. 
Bibliography. 
1. Briggs, G. E. : The Development of Photosynthetic Activity during Germination. Proc. Roy. 
Soc., B., vol. xci, 1919-20. 
2 . -: The Development of Photosynthetic Activity during Germination of Different 
Types of Seeds. Ibid., vol. cxiv, 1922. 
3 . Chauveaud, G. : L’appareil conducteur des plantes vasculaires et les phases principales de son 
evolution. Ann. Sci. Nat. (Bot.), ser. 9, tome xiii, 1911. 
4 . Col, A. : Recherches sur la disposition des faisceaux dans la tige et les feuilles de quelques 
dicotyledones. Ibid., ser. 8, tome xx, 1904. 
5 . Compton, R. H.: Theories of the Anatomical Transition from Root to Stem. New Phyt., xi, 
1912. 
6. -: An Investigation of the Seedling Structure in the Leguminosae. Journ. 
Linn. Soc. (Bot.), xli, 1912. 
7 . Cramer, W. : ‘ Fatty Substances’ in Microtomist’s Vade Mecum (Lee), edit. J. B. Gatenby, 
London, 1921. 
8. Davey, A. J. : Seedling Anatomy of certain Amentiferae. Ann. Bot., xxx, T916. 
9 . PI ill, T. G., and DE Fraine, E.: The Seedling Structure of Centrospermae. Ibid., xxvi, 1912. 
10 . Irving, A. A. : The Beginning of Photosynthesis and the Development of Chlorophyll. 
Ibid., xxiv, 1910. 
11 . Lubbock, Sir J. (Lord Avebury) : On Seedlings, vol. i, pp. 360-2. London, 1892. 
12 . Petit, L.: Le petiole des dicotyledones. Mem. Soc. Sci. Bordeaux, ser. 3, tome iii, 1887. 
13 . -: Nouvelles recherches sur le petiole des phanerogames. Actes Soc. Linn. Bordeaux, 
vol. liii, ser, 5, tome iii, 1889. 
14 . Tansley, A. G., and Thomas, E. N. : The Phylogenetic Value of the Vascular Structure of 
Spermophytic Hypocotyls. Report Brit. Assoc., York, 1906. 
15 . Thiselton-Dyer, W. T.: Morphological Notes. VIII. On Polycotyledony. Ann. Bot., xvi, 
1902. 
16 . Thomas, E. N,: Seedling Anatomy of Ranales, Rhoedales, and Rosales. Ibid., xxviii, 
I 9 I 4* 
