The Exchange of Material between Nucleus and Cytoplasm in Peperomia sintenisii

At fertilization in Peperomia sintenisii globules of cytoplasm surrounded by a nuclear membrane are inclosed in the fusion nucleus. The cytoplasm globule gradually assumes the appearance of nuclear sap, after which the membrane around it disappears. This phenomenon seems to show that all of the essential constituents of cytoplasm can be changed to nucleoplasm. The appearance of a nuclear membrane when cytoplasm and nuclear sap meet, and the absorption of the membrane when nucleoplasm is on both sides of it, seem to show that the nuclear membrane is formed by the interaction of cytoplasm and nuclear sap. If the membrane is formed in the above manner, it is probable that the contents of the cytoplasmic vesicle could not be changed to nucleoplasm by a gradual exchange of material between the nucleus and cytoplasm, for all of the constituents of the cytoplasm could not pass through the membrane, because some would react with the nucleoplasm and thicken the membrane. Since, however, the cytoplasmic contents of the vesicle are changed, this change is probably due to some substance which has come from the nucleus. It is probable then that cytoplasm before being taken into a nucleus is changed by some substance which has passed from the nucleus, because it is not likely that Peperomia sintenisii differs from other organisms in such a fundamental activity of protoplasm. The passage of substance from the nucleus is probably continual and may be a means by which the "resting" nucleus controls the cytoplasm.