i 



1902] OAT THE DEVELOPMENT OF CERTAIN PIPERACEAE 335 



Cucurbita and Phaseolus ; or secondly, the food may be stopped 

 in transit between the nucellus and the embryo, and stored in 

 the endosperm, there to be held during the resting period of the 

 seed, and delivered over to the embryo only at the time of 

 sprouting, as in Ricinus, Zea, and apparently all Gymnosperms ; 

 or finally, the food supply for the developing embryo may be 

 stored in the nucellus itself until the time of germination, when 

 it is passed on to the embryo through the endosperm, as in 

 Saururus, Peperomia, Phytolacca, Canna, and others. 



IV. SUMMARY AND CONCLUSIONS. 



Campbell has shown (1899, p. 453) that the nearly ripe 

 embryo sac of Peperomia pcllucida differs from that of all other 

 Angiosperms studied up to that time in the presence of sixteen 

 free nuclei derived from the megaspore nucleus. The writer 

 found the same species to be peculiar also in the formation of 

 the endosperm nucleus by the fusion of eight of these embryo 

 sac nuclei, and in the persistence of seven others of these near 

 the wall of the sac, one of them near the egg in the position of 

 a synergid (Johnson, 1900^, p. 4). The ripe seed has a single 

 integument, contains an undifferentiated embryo of about fifteen 

 cells surrounded by a very small endosperm, which \s cellular 

 from the two-nucleate stage on, contains chiefly aleurone, and is 

 surrounded in turn by an abundant perisperm stored with starch^ 



The study of. several other species of Peperomia by Campbell 

 and the writer has shown that these agree with P, pcllucida in the 

 features noted. 



The development of the ovary, ovule, and embryo sac in 

 Piper and Heckeria differ widely in several respects from that 

 found in the related genus Peperomia. The ovary in both 

 genera seems to be syncarpous. Two integuments are found in 

 both. A tapeta! cell and a single megaspore are formed from 

 the archesporial cell in each genus. The megaspore gives rise 

 in the usual way to a seven-nucleate embryo sac. The anti- 

 podals and synergids are long-persistent. The embryo in the 

 ripe seed is very small, of forty or more cells in cross section, 

 and globular except for a very short suspensor. 



