Geophilous Species of Peperomia. 417 
supplementing, during the favourable season, the reserves from the seed by 
means of carbon assimilation. 
To adaptations of this nature may be ascribed the various known 
departures, from the primitive dicotyledonous type, exhibited by the 
seedlings of bulbous plants. A change of function accompanied by 
a necessary change of structure of the ordinary parts of a dicotyledonous 
seedling has occurred, without any suppression or non-development of the 
normal structures, and without the precocious development of plumular 
organs (cf. Text-figs. 1-9, p. 420). 
In this connexion, also, these Peperomias are of particular interest, for 
some species have apparently reached a higher state of development and 
specialization than others. In P. peruviana the leaf-like character of the 
absorbent organ and the cotyledonary character of the aerial leaf are quite 
unmistakable (cf. Text-figs. 3 and 4, p. 420), and a somewhat similar condition 
of affairs is seen in P. mexicana and P. pedicellata. In P. umbilicata , 
H. B. and K., the absorbent cotyledon appears to be rather less leaf-like, 
and in P. parvifolia it has become specialized as a club-shaped organ, and 
has lost nearly all trace of its leafy character (cf. Text-figs. 3-6, p. 420). 
There are, as is well known, examples of bulbous Dicotyledons in 
several other natural orders, which show pseudo-monocotyledonous modifi- 
cations in the mode of germination of their seedings. These modifications 
have been evolved in various ways ; in some cases, perhaps, by a fusion of the 
two cotyledons (apparently in some Ranunculaceae), or by the abortion of 
one of the cotyledons (as in Cyclamen ). All such cases are of interest when 
the question of the origin of Monocotyledons is considered ; for it is 
possible that a study of these aberrant forms may throw some light on the 
subject. The peculiar mode of germination of these geophilous Peperomias 
suggests a fresh point of view, and the interesting question is raised 
as to whether the evolution of the Monocotyledons from dicotyledonous 
ancestors may not have taken place along somewhat similar lines. 
Comparison with Araceae. 
Among monocotyledonous orders, the Araceae are the most nearly re- 
lated to the Piperaceae 1 ; they differ from the more typical Monocotyledons 
in some rather important points, and, according to Scott and Sargant 2 , the 
vascular bundle of the cotyledon in Arum and Arisaema does not show 
any trace of the double structure so common in the Liliaceae. In their 
external features, moreover, the seedlings of certain species of these two 
genera are strikingly similar to seedlings of the geophilous Peperomias 
(vide Fig. 49, PI. XXX, and cf. Text-fig. 1, p. 418). 
1 Campbell, Ann. Bot., xiv, xv, and xix. 
2 Scott and Sargant, Ann. Bot., v, xii, Fig. 14, PI. XXV, 
