4i5 
Geophilous Species of Peperomia. 
the two cotyledons remain within the seed for some time absorbing the 
reserve materials, and are not withdrawn until the reserves are exhausted. 
It is interesting to notice that these aberrant forms afford a close parallel 
in this respect, for at first in P. peruviana , and perhaps in all the other 
species, both cotyledons serve for a short time as absorbent organs. With 
the withdrawal of the aerial cotyledon, a cavity is left within the endosperm, 
which in P. peruviana is never entirely obliterated by the further growth of 
the absorbent cotyledon ; in fact the lamina of this organ retains its dorsi- 
ventral character within the seed, and, moreover, is seen to be slightly 
peltate, thus preserving the character of a foliage leaf (Fig. 16, PL XXIX ; 
Text-figs. 3-5, p. 402). P. peruviana thus exhibits somewhat imperfect 
or intermediate modifications of its seedling structure from the dicoty- 
ledonous type, which suggest that such modifications have been only 
comparatively recently initiated in this species. 
In P. parvifolia , however, the modification of the seedling structure 
seems to have proceeded still further towards the monocotyledonous ideal, 
for in this species the absorbent cotyledon is obovoid, or club-shaped, and 
has lost its dorsi-ventral character, so that apparently it fills the cavity of 
the endosperm (Fig. 22, PI. XXIX, and Text-figs. 5 and 6 , p. 420 ) 1 . The 
greater degree of specialization exhibited by the seedlings of this species is 
of considerable interest, for the adult plants of P. parvifolia^ P. verruculosa , 
and my own undetermined specimen from Pacechac 2 , are very strongly 
xerophytic, and form a closely related group, which must be considered to 
have advanced further in their adaptation to the bulbous habit than any 
other of the geophilous species. 
The absorbent cotyledon in P. umbilicata , H. B. and K. 3 , also appears 
to be more or less spherical (Fig. 30, PI. XXIX), and it is somewhat signifi- 
cant to notice that this species exhibits characters more markedly xerophytic 
than do its allies both in the structure of its leaves and of its fruits 4 . 
Further traces of the once normally dicotyledonous character of the 
seedlings, particularly in reference to the reduction of one of the aerial 
cotyledons to function wholly as an absorbent organ, are afforded by the 
occurrence of stomata and hydathodes 5 on their laminae. Stomata have 
been found in nearly all the absorbent cotyledons which have been 
examined ; they are quite normal in appearance, and starch has been found 
in the guard-cells in one or two cases, where they were situated near the 
middle of the lamina ; more commonly the stomata occurred at the apices 
1 Stomata were not distinguished, but only a single specimen was available for examination ; 
cf. p. 405. 
2 Vide p. 407. 
3 No. 631, Bourgeau, Santa Fd, Valle de Mexico, in Herb. Kew. 
4 For the other Mexican and Central American bulbous species, vide p. 408. 
5 Hydathodes were found in one case out of about five seedlings of P. peruviana examined ; 
they were situated near the base of the lamina on the lower surface. 
