190 Sinnott . — The Evolution of the Filicinean Leaf -trace. 
the slender trace and by the large petiolar bundle of the same leaf, it is im- 
probable that it has had much influence in producing the complications 
of the foliar vascular system. The stele and the leaf-trace have developed 
almost independently and the latter has had little influence in moulding the 
former. 
9. The condition found in the base of the trace in any fern was probably 
once present throughout the whole leaf-bundle. 
10. The simple condition in the upper part of the leaf may possibly be 
regarded as primitive. 
11. The histological influence of the stele is sometimes carried up into 
the base of the petiole, especially in cases of reduction, where the petiolar 
bundle, better than the lower part of the leaf-trace, retains conditions which 
may be regarded as primitive. 
12 . In the Filicales, as in all other vascular plants, the leaf-trace is the 
seat of ancestral characters. 
The writer is much indebted to Professor E. C. Jeffrey, Professor M. A. 
Chrysler, Mr. A. J. Eames, and the authorities of the Botanic Garden of 
Harvard University for aid in securing material, and to Professor Jeffrey 
for helpful advice during the course of the work. 
This investigation was carried on in the Phanerogamic Laboratories of 
Harvard University. 
Harvard University. 
June , 1910. 
Bibliography. 
1 . Bertrand, C. Eg., and Cornaille, E. : Etude sur quelques caracteristiques de la structure 
des Filicinees actuelles. I. Trav. et M6ra. de 1 ’Univ. de Lille, 1902. 
2 . Bertrand, P. : Etudes sur la fronde des Zygopteridees. Lille, 1909. 
3 . Boodle, L. A. : On the Anatomy of the Hymenophyllaceae. Ann. Bot., vol. xiv, 1900. 
4 . : On the Anatomy of the Schizaeaceae. Ann. Bot., vol. xv, 1901. 
5 . : On the Anatomy of the Gleicheniaceae. Ann. Bot., vol. xv, 1901. 
6. Bower, F. O. : The Origin of a Land Flora. London, 1908. 
7 . — — : Studies in the Morphology of Spore-producing Members. IV. Phil. Trans. 
Roy. Soc., B., vol. cxcii, 1899. 
8. : The Anatomy of Plagiogyria . Ann. Bot., vol. xxiv, 1910. 
9 . Brebner, G. : On the Anatomy of Danaea and other Marattiaceae. Ann. Bot., vol. xvi, 1902. 
10 . Chandler, S. E. : On the Arrangement of the Vascular Strands in the ‘ Seedlings ’ of certain 
Leptosporangiate Ferns. Ann. Bot., xix, 1905. 
11 . Chrysler, M. A. : The Nature of the Fertile Spike in the Ophioglossaceae. Ann. Bot., 
vol. xxiv, 1910. 
12 . Compton, R. H. : The Anatomy of Matonia sarmentosa. New Phytologist, vol. viii, 1909. 
13 . Farmer, J. B., and Hill, T. G. : On the Arrangement and Structure of the Vascular Strands 
in Angiopteris eveda and some other Marattiaceae. Ann. Bot., vol. xvi, 1902. 
