404 Hill ’ — The Morphology and Seedling Structure of the 
of the first and succeeding plumular leaves differs from that of the aerial 
cotyledon in being circular in outline and truly peltate, with the insertion of 
the petiole in the middle of the lamina. It is a somewhat delicate structure, 
without prominent veins, which becomes thin and membranous when dried 
(Figs. 10-12, PI. XXIX). In a transverse section there is seen to be a layer of 
clear, colourless, and sharply defined water-storing tissue on both the upper 
and lower sides of the lamina, some three cells in thickness, between which 
comes the narrow belt of assimilating tissue. This latter consists of three 
rows of cells, the upper one being the palisade-layer of short cells, with two 
layers of mesophyll cells below, and all containing chlorophyll. Stomata 
and hydathodes occur in the lower epidermis, and the latter occur sparsely 
on the upper epidermis, they take the form of a protruding glandular cell 
with a basal cell below ; they are also found on the petioles. 
A transverse section of one of these young bulbs shows that the brown 
colour is due to the old and dead outermost layer of cells, which have been 
cut off by a layer of hypodermal cork, some four to six cells in breadth. 
The outermost layer of the bulb is apparently a true epidermis, since the 
bulb seems to be formed from the hypocotyl. The radicle of the embryo 
may persist for some time, growing in length and producing lateral branches, 
though as a rule, shortly after the development of the first plumular leaf, 
new roots, which ramify extensively, arise from the sides of the little bulb, 
and soon replace the primary root (Figs, n and 15, PI. XXIX). The young 
bulb, at first white externally, soon becomes of a bright brown colour, 
and at this stage is covered, like the roots, with fairly long epidermal hairs 
(Fig. 10, PI. XXIX). 
Owing to the absence of certain stages in the development of the bulbs 
it is not clear how the ‘ hairs ’ arise, for they do not occur on the hypocotyl 
of the seedling, though root-hairs are found in abundance on the radicle. 
The old bulbs or corms of this species (P . peruviana) are about 8 mm. in 
breadth by 10-12 mm. in length ; they are more or less spherical, but with 
age often become somewhat irregular in shape, and the roots, which are 
adventitious in origin, are scattered over the base and sides (Figs. 1 and 2). 
When the plants were collected in February, they were in full vigour, with 
a crown of leaves and inflorescences, and the oldest fruits were already ripe ; 
it is possible that the germinating seeds which were found may have been 
produced this same season 1 . 
P. PARVIFOLIA. 
P. parvifolia , C. DC. The fruit in this species differs considerably 
from that described above ; it is about 1-4 mm. long by 1 mm. broad, and 
contains a seed measuring about -8—9 mm. by -65 mm. (Fig. 18, PI. XXIX). 
1 Cf. Johnson, 1 . c., vol. xxxiv, p. 330. 
