710 
Botany. — “Dichotomy and lateral branching in the Pteropsida”. 
By Mr. J. C. Scnourr. (Preliminary communication). *) 
(Communicated in the meeting of Oct. 26, 1912). 
In 1900 and more recently ?) Jerrrey argued that the correspond- 
ence in structure of Filicales, Gymnosperms and Angiosperms jus- 
tified the union of these three groups into a higher group, that of 
the Pteropsida. 
Palaeontological research has later rendered this conclusion more 
probable *). 
When on this account we assume a closer relationship between 
these groups, there naturally still remain many great differences 
between them; one of these is in the method of branching. For 
whilst the Gymnosperms and Angiosperms without exception branch 
by means of axillary buds (apart from adventitious buds), we find 
the ferns are typically dichotomous‘). Mertens *) described long 
ago in ferns lateral buds in every kind of position (axillary, 
next to the insertion of the leaf, under the insertion, half on the 
stem and half on the petiole) but all this has been explained by 
VrLenovsky as due to the formation of “stable adventitious buds °). 
The distinetion between dichotomy and lateral branching has always 
been considered by all writers to be of great phylogenetic importance. 
An investigation on branched tree-ferns has led me to the idea 
that there may perhaps be no difference in principle between these 
various modes of branching; in other words, that dichoto- 
mous branching would be, in its essence, the same as the lateral 
branching of ferns or Angiosperms. The fine material, mostly col- 
lected by Mr. Koorpers, on which this investigation has been made, 
will be described exactly in the detailed publication. Here I only 
remark that in these trees ordinary dichotomy can sometimes take 
place, as a reaction fo certain pathological processes, with a normal 
1) A detailed paper, illustrated by plates, will appear on this subject in the Recueil 
des Travaux botaniques néerlandais. 
2) E. C. Jerrrey. The Morphology of the Central Cylinder in the Angiosperms ; 
Canadian Inst. Trans., Vol. 6, 1900. -— The Structure and Development of the 
Stem in the Pteridophyta and Gymnosperms ; Philos. Trans. R. Soc. London, Vol. 
195, 1902. 
3) See e.g. D. H. Soort, Studies in fossil. Botany, 2nd Ed. London 1908/09, 
p. 638, 
4) J. VELENOVSKY. Vergleichende Morphologie der Pfianzen. Prag 1905, p. 245. 
5) G. Merrentus. Ueber Seitenknospen bei Farnen, Abhandl. math-phys. Classe 
k. Siichs. Ges d. Wiss. Bd. 5, 1861, p. 611. 
6) lc. p. 247. 
