320 
T. G. Hill and E. de Fraine. 
sheath and, ultimately, ending blindly in the aqueous tissue. 
Nothing comparable to these facts has been observed in any of the 
other Centrospermae examined. 
The Cactaceae provide similar instances. It was shewn some 
years ago by Ganong 1 that the form of the seedling corresponds very 
closely with that of the adult plant. The study of the seedling 
structure has shewn that this assumption of the adult habit has had 
a profound influence upon the seedling anatomy. 3 
In the leafy forms, e.g., Pereskia, Opuntia and Nopalea, the 
sequence of events in the transition-phenomena is reasonably 
straight-forward, the Ancmarrhena- type being dominant; but in 
those which have a succulent seedling the transition is very variable. 
Type 3 is the one followed, but the details vary considerably 
according to the morphology of the seedling; for the cotyledons, as 
such, may not be present, so that the vascular supply of other 
members plays the prominent part in the phenomenon. In 
Echinopsis the behaviour of the seed-leaf-traces depends almost 
entirely upon the degree of development of the vascular supply of 
the tubercle. Thus when the tubercle is well differentiated its bundles 
may play the more important part in the transition-phenomena. 
Similarly in Mamillaria pusilla, which has no cotyledons, the 
epicotylar strands assume the part normally played by the cotyle¬ 
donary traces in the transition. 
These and similar facts shew the important influence which 
morphology, and consequently physiology, exerts upon the structure 
and gives much weight to the view that in many cases anatomical 
detail is of no value in determining phylogeny. 
The examination of Pevsoonia lauceolata forms the coping stone, 
as it were, to our thesis—the influence of the adult structure upon 
the seedling. 
The Seedling-Anatomy of Persoonia lauceolata , Andr. 
(N. O. Proteace^;). 
Our attention was first drawn to the seedlings of the Proteaceae 
by the publication of the interesting results obtained by Fletcher. 3 
1 Ganong, W. F. Contributions to a Knowledge of the Mor¬ 
phology and Ecology of the Cactacea; II—The Comparative 
Morphology of the Embryos and Seedlings. Ann. Bot., 1898, 
XII. 
2 de Fraine, E. The Seedling Structure of Certain Cactaceae. 
Ann. Bot., 1910, XXIV. 
8 Fletcher. Illustrations of Polycotyledony in the genus 
Persoojiia , with some reference to Nuytsia. Proc. Linn. Soc., 
New South Wales, 1908, XXXIII, Pt. 4. 
