1910] BROWN—NUCLEUS AND CYTOPLASM IN PEPEROMIA 193 
Summary 
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 constit- 
uents of cytoplasm can be changed to nucleoplasm. 
The appearance of a nuclear membrane when ote ae and 
nuclear sap meet, and the absorption of the membrane when nucleo- 
plasm 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 cyto- 
plasmic 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. 
The material, which made these observations possible, was col- 
lected in Jamaica by Professor D. S. JoHNson, to whom the writer 
is greatly indebted. 
THE JoHNs HopKins UNIVERSITY 
ALTIMORE, Mp. 
LITERATURE CITED 
1. ALLEN, C. E., The early stages of spindle formation in . pollen mother cell 
of Larix. Acaiats of Botany 17: 281-312. pls. 14, 15. 1903. 
- Brown, W. H. , The nature of the embryo sac of ceil Bor. GAZETTE 
46: 445~460. bis. 31-33. 1 : 
- Byxper, Eprra, The devslopeent of the karyokinetic spindle in the pollen 
mother cells of Lavatera. Proc. Cal. Acad. Sci. Bot. III. 2:63-82. pls. 
10-13. 1900 
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