Autonomy of Plasmatic Membranes 159 



the old conception would have it, a ground-substance of 

 protoplasm, mixing constantly by its movements, and 

 therefore not organized in the ordinary sense. This is 

 most clearly seen in the Characeae. Here it consists, first 

 of all, of a moving portion and of a resting part that 

 contains the chlorophyll grains. When, sometimes the 

 green plastids are torn from their position, and carried 

 away by the current, one sees that they did not adhere 

 separately to the plasmatic membrane, for they are not 

 carried off singly, but in bands and groups, while within 

 these the grains retain their mutual position and distance. 

 Neither does the moving part form a whole, for the ra- 

 pidity of the current is not at all everywhere the same 

 on a cross-section. It is greater near the chlorophyll- 

 grains than next to the wall of the vacuole, and further- 

 more it increases from the two indifferent zones toward 

 the center of the green areas which are separated by them. 

 With declining vital energy the more torpid currents are 

 the first to suspend movement, while the more rapid ones 

 continue to move, and with decreasing rapidity the width 

 of the current diminishes at the same time. 



Quite generally speaking, the granular plasm seems 

 to consist, in the plant-world, of moving and of resting 

 parts, the limits of which can be shifted by more or less 

 favorable life-conditions, or can also shift spontaneously 

 in the course of development, adapting themselves to 

 changing needs. 



The latter condition is illustrated by the beautiful in- 

 vestigations by Dippel, Cruger, and Strasburger on the 

 relations between the plasma-currents and the internal 

 sculpture of the cell-wall.^* For along those places where 



6*Dippel. Abhandl. Naturf. Ges., Halle. 10: 55. 1864. Cruger, 

 H. Westindische Fragmente. Bot. Zeit. 13: 623. 1855. Stras- 

 burger, E. Jenaische Zeitschr. Natunviss. 10: 417. 1876. 



