414 Hill. — The Morphology and Seedling Structure of the 
General Considerations. 
Several points of general interest and of somewhat wide bearing are 
suggested by the facts which have been detailed in the foregoing pages ; 
but, in the first place, it will be best to summarize the evidence which has 
been obtained from the study of these geophilous Peperomias. The internal 
structure of the seed has been found to agree with that which obtains in 
normal species of the genus, and there is little doubt that the early history 
of the embryo follows the usual course. In its germination, however, it 
reveals some striking aberrations from the dicotyledonous type common 
to the majority of the species, for the seedling is, in appearance, 
monocotyledonous. 
Although the embryo is dicotyledonous in structure, the mono- 
cotyledonous character of the seedling is due to the fact that the two 
cotyledons show a division of labour ; for whereas one serves as an 
absorbent organ, the other is mainly, if not entirely, an assimilating organ. 
That we have really to deal with two cotyledons in these species seems to 
me to be proved by the following considerations. 
In the first place, the initial pair of leaves of the young seedling are 
always opposite to one another (cf. Fig. 13, PI. XXIX), having their upper 
surfaces in contact within the seed, and the seedlings appear to agree very 
closely, in the youngest stages, with the dicotyledonous embryo of P.pellucida. 
Secondly, the vascular bundles, which are similar in structure in both the 
petioles, fuse together below the plumule at the same horizontal level, and 
appear to take equal shares in the composition of the central stele of the 
hypocotyl and root (cf. Fig. 14, PI. XXIX). In the third place, it must be 
borne in mind that these geophilous species form a very small subgroup of 
a large genus whose various species, with these exceptions, show, as far as 
we know, a perfectly normal dicotyledonous embryo ; and we have every 
reason for supposing that the structure of the seedlings is homologous 
throughout the genus. 
Certain features which are noticeable during germination suggest that 
the monocotyledonous tendency is a fairly recent acquisition in the genus, 
and is, moreover, directly correlated with the adoption and development of 
the bulbous habit L Amongst such features, the sharp bend or hook 
exhibited by the petioles of both of the cotyledonary leaves may be 
mentioned (cf. Figs. 5, 6, and 13, PL XXIX). This no doubt is a reminiscence 
of the time when both cotyledons were epigeal. Now only one cotyledon 
becomes aerial and bears the pressure of the soil on its sharply bent 
petiole (Fig. 6). In a normal species such as P . pellncida * 1 2 , it is seen that 
1 Cf. Darwin, C., The power of movements in Plants, p. 97. 
2 Cf. Text-fig. 1, p. 402, and Text-figs. 1 and 2, p. 420, also v. Johnson, Eot. Gaz., xxxiv, 
Figs. 31, 37, 39 > PL x - 
