Autonomy of Vacuoles 153 



thinness. But they are clearly and distinctly visible in the 

 tentacle-cells of some insectivorous plants, especially of 

 the Drosera rotundifolia and D. intermedia. The process 

 of aggregation, discovered by Darwin, 52 taking place here 

 during the digestion of the prey, belongs to the most in- 

 teresting phenomena that the life of a cell presents for 

 our admiration. In the resting tentacle-cells there lies 

 usually a large vacuole containing red cell-sap. Under 

 the influence of stimulation it separates into several, and 

 soon into numerous smaller ones. These contract, while 

 secreting part of their contents, and are now carried 

 through the cells by the currents of the granular plasm, 

 with great rapidity, and in the most various directions. 

 Thus they lie as red vesicles in unstained sub- 

 stance, and can therefore be seen very distinctly. Dur- 

 ing these movements they undergo striking changes of 

 form ; sometimes they are drawn out into long tubes, and 

 thereupon split into numerous small globules, sometimes 

 two or more unite to form larger vesicles. Toward the 

 end of the phenomenon this last process has the pre- 

 cedence, and finally all the sap-bubbles have again united 

 into one, of the original volume. 53 



The above mentioned phenomena of aggregation, and 

 the division of the vacuoles, as it is so frequently ob- 

 served in plasmolysis placed the ability of these organs 

 to multiply by this process beyond any doubt. From the 

 analogy of these structures with the chromatophores I 

 then deduced the assumption, that "like the amyloplasts, 

 they can be produced in no other way than by division." 54 



52 Darwin, C. Insectivorous Plants. Chap. III. 1875. 



53 Vries, H. de. Ueber die Aggregation im Protoplasma von 

 Drosera rotundifolia. Bot. Zeit. 44: 1, 17, 33, 57. 1886. 



54 Vries, H. de. Plasmolytische Studien iiber die Wand der Vac- 

 uolen. Jahrb. Wiss. Bot. 16: 505. 1885. 



