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. 9 



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 1 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. 



