Stimulus to Formation of Cell Membranes 31 
six filaments. These protoplasmic connections persist 
for some time even when the spores have been divided 
into two, four, or more constituent parts.® 
An experiment which has already become famous 
appears to indicate that the intercellular bridges, as if 
they were successors of the vibratile protoplasmic fila- 
ments, substituted for them, are traversed incessantly by 
nervous currents or discharges emanating from the 
nucleus. For this experiment we are indebted to Pfeffer. 
After having detached by plasmolysis the cell mem- 
brane of the nucleated protoplasmic body of a plant cell, 
and dividing the cell into halves, one containing a nucleus 
and one without any, he observed that only the nucleated 
half had surrounded itself with a new cell membrane. 
If however, the part deprived of the nucleus remained 
united to the nucleated fragment even by only a very 
fine protoplasmic filament, it also was capable of secreting 
its little cellulose membrane. 
Pfeffer varied his experiment also in the following 
manner. He prepared cells of a moss protonema in such 
a way that an entirely isolated, anucleate mass of proto- 
plasm remained united to the neighboring cell which con- 
tained a nucleus by means of thin filaments piercing the 
cell wall. In this case a membrane was formed round 
the anucleate fragment. But the membrane was not 
formed if the neighboring cell had been itself deprived 
of its nucleus. 
In the formation of this cellular membrane in 
anucleated parts of the cytoplasm united by protoplasmic 
filaments with other nucleated portions, the maximum 
intervening distance observed by Pfeffer was 3.7 mm. 
°Oscar Hertwig: Die Zelle und die Gewebe. Zw. Buch, P. 34, 
35. Fig. 16, 17. 
