399 
Geophitous Species of Peperomia . 
Kunth, which have been described by Johnson 1 , it will not be necessary to 
do more than point out a few of the most important features of their internal 
structure. As in that species, the single integument appears to be composed of 
two cell-layers, which ripen to form a brown investment to the seed ; within 
the testa the bulk of the seed is composed of the perisperm, the embryo with 
its endosperm occupying only a very small space at the apex of the seed 
just under the micropyle (Figs. 3, 8, 29, PI. XXIX ; and Fig. 3 1 , PI. XXX). 
The cells of the perisperm are closely packed with starch, which is entirely 
absent from the endosperm-tissue in the dormant seed. The outermost 
layer of the perisperm differs somewhat in the structure of its cell-walls and 
in the nature of the cell-contents from the rest of this tissue ; with Methylene 
Blue and Eosin the walls of this layer take on a deeper coloration than 
those of the inner cells, but with Water Blue they remain unstained, while 
the walls of the mass of the perisperm stain violet blue. The cell-con- 
tents also differ in that some other small bodies besides starch are present, 
which stain violet with Water Blue and orange yellow with Iodine, and 
one is reminded in general appearance of the aleurone layer in the 
endosperm of grasses. Besides starch, some other highly refractive 
bodies, whose nature is as yet undetermined, are found in the general 
perisperm-cells. 2 The structure of the embryo and endosperm, their 
relations to one another in the dormant seed, and the earliest stages in 
the germination of the embryo in these geophilous species, appear to agree 
in all essentials with the account given for P. pellucida (vide Text-figs. 1 
and 2, p. 402). 
The interesting problem of the relation of the endosperm to the peri- 
sperm, in this and other genera with a similar seed structure, is discussed 
by Johnson 3 . He produces a considerable amount of evidence to show 
that the food-material stored in the perisperm can only be utilized by the 
embryo with the aid of the intervening thin sac of endosperm-tissue, and 
some further support is lent to this view by a somewhat inconclusive paper 
by Lewis 4 on the development of the seed of Phytolacca decandra. Sec- 
tions of the seeds of my own species in an advanced stage of germination 
show a definite deeply staining layer of compressed and disorganized cells 
attached to the perisperm and surrounding the cotyledon (Fig. 1 6, PL XXIX ; 
cf. also Text-figs. 3-5, p. 402). This layer appears to be the remains of the 
endosperm, through which the reserve materials must have passed from the 
perisperm to the developing embryo. The sheathing endosperm was also 
very clearly seen in a young seedling of P. umbilicata , FI. B. and K. 5 (Fig. 
30, PL XXIX). 
1 Johnson, Bot. Gaz., vol. xxx, p. 7; ib., vol. xxxiv, p. 329; Campbell, Ann. Bot., vol. xv, 
p. hi. 2 Cf. Johnson, 1. c., p. 6. 
3 Johnson, xxxiv, pp. 334-5. 
4 Lewis, Johns Hopkins Univ. Circ., New Ser., 1905, No. 5, p. 34, with figures. 
5 Vide p. 398. 
