THE 
NEW PflYTOIiOGIST. 
Vol. XVI, Nos. i & 2 . 
Jan. & Feb., 1917. 
[Published March 19th, 1917.] 
OBSERVATIONS ON THE EVOLUTION OF 
BRANCHING IN THE FILICALES.* 
By Birbal Sahni, B.A., B.Sc., 
Research Student and Former Scholar , Emmanuel College, Cambridge. 
[With One Figure in the Text]. 
I. Introduction. 
HE starting point of this paper was an attempt to see how 
A far our conception of the branch as a potential individual 1 
finds support from the recapitulation by the branch of the sequence 
of structural changes undergone by the main axis during its ontogeny. 
In this connexion a previous statement by the late Professor 
Gwynne-Vaughan 2 was particularly suggestive, namely, that “ the 
ontogeny of the vascular system of the plant as a whole is very 
frequently repeated, although more or less imperfectly, in the 
development of its lateral branches ”—a statement which is sub¬ 
stantiated by the researches of Stenzel 3 on several species of 
Aspidium, Alsophila excelsa, Blechuum and Struthiopteris germanica, 
and of Mettenius 4 on various other dictyostelic Ferns; by those of 
Gwynne-Vaughan himself ( loc . cit .) on a number of soleno- 
stelic and dictyostelic Ferns, and, more recently, by those of 
Professors Lang 5 and Bower 6 respectively on the Ophioglossaceae, 
♦Dissertation presented for the Sudbury-Hardyman Prize, 1917, at 
Emmanuel College, Cambridge. 
1 Braun, Alex, Betrachtungen u. d. Erscheinung d. Verjiingung in der 
Natur., 1851, p. 25. 
1 Gwynne-Vaughan, Annals of Botany, 1903, pp. 724-5. 
8 Stenzel, Verhandlungen der K. Leop. Carol. Akad. der Naturforscher, 
1861, p. 16. 
* Mettenius, Abhandlungen der kgl. sachs. Ges. 1861, Vol. IX. Ueber den 
Bau von Angiopteris, p. 499. 
‘ Lang, W. H., Annals of Botany, 1913, Vol. XXVII, i. p. 203 and 1915, 
Vol. XXIX, p. 1. 
6 Bower, F. O., Annals of Botany, 1910, p. 423 ; 1912, p. 269 ; 1913, p. 443 ; 
1914, p. 363 ; 1915, p. 495. 
