Campbell . — The Embryo-Sac of Peperomia. 1 1 5 
or not is doubtful, and the question whether the synergidae 
are, so to speak, sterile archegonia, or whether they are 
simply vegetative prothallial cells which become specialized 
for assistance in fertilization, cannot now be answered. The 
nearest approach to the structures found in Peperomia occurs 
in Gnetum 1 , where no archegonium is formed, but the gene- 
rative nucleus from the pollen-tube fuses with one of the free 
nuclei in the upper part of the embryo-sac. 
That the fusion of the polar nuclei of the typical Angio- 
sperms is in no sense a sexual process is borne out by the 
condition of affairs in Peperomia. The fusion of such a mass 
of nuclei is not conceivable as a sexual process, and is with 
little question, as already stated, a nutritive process, or 
perhaps a stimulus to active division in the endosperm- 
formation, or secondary growth of the prothallial tissue, 
which is to nourish the young embryo. This has no equivalent 
among either Archegoniates or Gymnosperms, and until 
further evidence is offered, may be assumed to have arisen 
among the lower Angiosperms, and to have become restricted 
to the special polar nuclei as the number of nuclei was reduced 
from sixteen to eight. The fusion of the second generative 
nucleus with the complex must also be assumed to be 
a special development. The second generative nucleus dis- 
charged into the embryo-sac, not having an egg with which 
to conjugate, might very naturally fuse with the only available 
nucleus, i. e. the endosperm-nucleus. That the tissue arising 
from this compound nucleus should show evidences of its 
hybrid character, where cross-pollination has taken place, is 
what would be expected, and by no means implies that the 
hybrid endosperm is in any proper sense of the word an 
embryo. The small cells developed individually about the 
nuclei which do not participate in the endosperm-formation 
in Peperomia . , while they are not grouped together, must 
nevertheless be regarded as equivalent to the antipodal group 
of the typical Angiosperms, where the position of these cells 
1 Lotsy, Contributions to the Life-history of the Genus Gnetum. Ann. du Jar. 
Botanique, Buitenzbrg, xvi, 1900, p. 46. 
