420 
Morphologie, Befruchtung, etc. — Varietäten. 
Worsdell, W. C., The origin of the “flower”. (Science 
Progress. Vol. II. N°. 6. p. 255—262. 1907.) 
A typical flower is homologous with an ordinary leafy shoot, 
and it is probable that each type of floral leaf, whether sepal, petal, 
stamen, or carpel, has been derived by modification of green foliage 
leaves. The petals are to be regarded as a comparatively recent 
development, derived (as maintained by Grant Allen, Nägeli, 
Drude, and Celakovsky) from stamens. This view is supported 
by the study of double flowers. Turning to the phylogenetic aspect 
of the subject, we find in the Palaeozoie period a group of plants, 
the “Seed-ferns,” which bore large complex Fern-like sporophylls 
of two kinds, some producing male sporangia and others seed-like 
organs. These “Seed-ferns” may be regarded as intermediate between 
the true Ferns and Gymnosperms generally, while in the succee- 
ding Mesozoic period there is another group, the Cycadeoideae or 
Bennettiteae intermediate between the “Seed-ferns” and the modern 
Cycads. The male organs of the Cycadeoideae much resemble those 
of the “Seed-ferns” but are somewhat less complex. In the female 
organs reduction has gone much further, the large seed-bearing 
fronds of the “Seed-ferns” being replaced by slender stalks each 
bearing a single seed. Scattered amongst them are sterile sporophylls 
forming a pseudocarp. Both male and female sporophylls have been 
reduced in size and complexity at the same time that they have 
been segregated from the foliage leaves. In the reproductive branch 
of the Cycadeoideae we see a representative of the primitive or an- 
cestral “flower”. It is quite likely however that the Angiosperms 
were not derived from this group but sprang from a stock lower 
down nearer the “Seed-fern” stem. A. Robertson. 
Tansley, A. G. and E. N. Thomas. The phylogenetic value 
of the vascular structure of spermaphytic hypoco- 
tyls. (Rept. Brit. Assoc. York (1906). p. 761—763. 1907.) 
The authors point out that the intra-seminal development of the 
embryo and the occurrence of a hypocotyledonary-region renders the 
consideration of the early ontogeny of the spermaphytes a very 
different matter from that of the Ferns. At the same time it is main¬ 
tained that the anatomical features of the vascular System of the 
hypocotyl have a real phylogenetic value. 
In the characteristic Dycotyledonous type of “transition” the 
base of each cotyledon contains a “double bündle” with two phloem 
groups at the ends of the arms of a V the apex of which is occu- 
pied by the xylem. At, or just below, the cotyledonary node the 
xylems of the bundles of the two cotyledons become exarch and 
join up to form the diarch xylemplate of the root Stele. At the 
same time the four phloem groups fuse in pairs on either side of 
the xylemplate. 
In some plants two lateral bundles also exist at the base of the 
cotyledons in addition to the “double bündle”. These may either 
join on to the “double bündle” below or they may run down into 
the node and fuse with the corresponding laterals from the other 
cotyledon. In some cases these fused laterals join on to the sides of 
the diarch root Stele without materially affecting its structure, but 
in others their xylem Strands form the intercotyledonary poles of a 
tetrarch root Stele. In other cases again the double bündle in the 
