Tansley and Thomas. 
transitional to the Cycads. It is these researches 1 that have paved 
the way for more recent discoveries, and so well that when they 
came no surprise was evinced. But the value of anatomical 
characters as indicating affinity has been fully vindicated. 
1 e.g. Williamson and Scott, “ Further Observations &c.,” 
Ft. hi., Phil. Trans. B, Vol. rS6, 1895. 
EXPLANATION OF THE PHOTOGRAPHS ON PLATE II. 
All the sections have been prepared by Dr. Fr. Krantz of Bonn, from 
blocks in the Williamson Collection derived from Grand ’Croix. The 
numbers cited in brackets are the Cabinet numbers of the specimens 
figured. The photographs were taken by Mr. W. Tams of Cambridge. 
Trigonocarpus pusillus, Brongn. 
Photo. 1. Nearly median longitudinal section through the seed 
shewing micropyle and pollen-chamber. The body c f the nucellus 
is occupied by the prothallium. E., stripped epidermis of nucellus ; 
T, portion of wall of nucellus cut tangentially and shewn on a 
large scale in photo. 4. A more highly magnified view of the apex 
is given in photo 3. (1486a) x 12. 
rhoto. 2. Longitudinal section from the same seed just touching the 
side of the pollen-chamber at its insertion. The section is slightly 
oblique and traverses the axis of the seed about half way up. G, G. 
gaps on either side due to stripping of epidermis from nucellus. 
(14866) x about 12. 
Photo. 3. Apex of seed in section 1486a (photo. 1) more highly 
magnified. C, collar at base of nucellar beak ; S, remains of 
septum or floor of pollen-chamber; S.T, remains of sarcotesta. 
x 21. 
Photo. 4. Portion of wall of micellus (T, photo. 1) with sinuous 
tracheal strand. X 120. 
Polylophospcrmum stephancnse, Brongn. 
Photo. 5. Longitudinal section. M, micropyle ; E, lining of testa ; PC. 
pollen-chamber ; O, orifice of piothallial vesicle. (1492a) x about 3. 
Photo. 6. Reticulated tracheide from nucellus of the same specimen, 
a scalariform element is seen below, x 275. 
Photo. 7. Scalariform tracheides from the nucellus of an adjacent 
section. (14926) x 265. 
Photo. 8. Other scalariform tracheides. (1492a) x 280. 
Photo. 9. Tracheal strands with junction at A. (14926) x 200. 
Photo. 10. Fragment of wall of nucellus in tangential section shewing 
tracheal strands (darker) coursing 011 the surface. (14926) x 30. 
ROOT-STRUCTURE IN THE CENTRAL CYLINDER OF 
THE HYPOCOTYL. 
m he transition-phenomena in the seedlings of Piper cornifolium 
and Peperomia maculosa described by Mr. T. G. Hill in the 
February number of this Journal (Vol. III., p. 46) are of consi¬ 
derable interest to students of the vascular structure of Angio- 
spermous seedlings. 
The case recorded as occurring in the former plant is not, 
however, as he supposes, hitherto undescribed. 
It appears to be an extreme example of the type in which a 
diarch root-stele is formed at or immediately below the cotyledonary 
node entirely by the two cotyledon-traces, so that the whole or 
