STUDIES OF THE DEVELOPMENT OF PEPEROMIA HISPIDULA 387 
could be expected now, even if this were its nature. There is no 
evidence of the fusion of a second male nucleus in the endosperm 
group. 
The occasional formation in P. hispidula of peripheral cells by the 
enclosure of one or two of the 16 nuclei of a sac by cell walls is probably 
to be regarded as a partial reversion to the fate characteristic of part of 
these nuclei in all of the 10 other Peperomias studied (Johnson, 1900a; 
Brown, 1908; Fisher, 1914). No instances of these peripherals were 
seen in my earlier work on P. hispidula (Johnson, 1907). The agree- 
ment of the other 10 species with each other is strong evidence that the 
embryo-sac with half a dozen peripheral cells is the more primitive 
type characteristic of the genus, from which the P. hispidula type, 
with few or none, has been derived. 
There seems no particular reason for comparing the i or 2 periph- 
eral cells of P. hispidula, when formed, or the 6 peripherals of other 
Peperomias with the antipodals of other angiosperms, except in so far 
as they are left over after the essential structures of the embryo sac 
have been organized. They certainly give no evidence of being sterile 
egg apparatuses, such as Porsch (1907) would expect to find in a primi- 
tive angiosperm. 
Concerning the physiological cause and significance of the peculiar 
type of organization of the embryo-sac and endosperm nucleus found 
in P. hispidula we know nothing. Brown (1908), has suggested that 
the globular form of the mother cell gives all four of the megaspore 
nuclei formed in it an equal advantage in space and food supply. But 
it is to be remembered that other rounded mother cells may give rise 
to but one functional megaspore while in other angiosperms the compo- 
site embryo sacs are decidedly elongated. Among the latter are to be 
counted Gunnera, Lilium, and probably Piper, and many others with 
elongated sacs can be added to this list when the point at which chromo- 
some reduction occurs has been determined. 
Of the significance of the multiple fusion in the formation of the 
huge endosperm nucleus nothing definite can be said except to make 
the oft-repeated statement of fact that where two or more nuclei are 
left together in one protoplast they usually fuse to one nucleus. In 
the present instance the effect is to practically overcome the disparity 
in size of nucleus and protoplast (cf . figs. 58 and 88) . The only evident 
physiological advantage of a fusion of the 14 nuclei into a single nucleus 
is that of forming a large^ nuclear unit adequate for the control of the 
