CHANGES IN CELL-ORGANS OF DROSERA ROTUNDIFOLIA. 389 
that the aggregated masses were “protoplasm.” He states 
the two opposing theories thus : 
I, “ My father’s view, that the aggregated masses consist of 
protoplasm, and that their movements are simply due to their 
own contractility, excited by various external agencies.”’ 
II. “ Professor Cohn’s view, which appears to be that the 
ageregated masses consist of condensations of cell-sap, and as 
a necessary corollary that the movements are impressed on the 
masses by some kind of protoplasmic action external to the 
masses.” 
That the latter view is the correct one was proved by 
Schimper, Gardiner, and De Vries, all of whom subsequently 
studied the phenomenon, and came to the conclusion that it is 
the contents of the vacuoles, and not the protoplasm, which 
give rise to the phenomenon described by Darwin. 
Schimper! compared the condition of the cells before and 
after stimulation in Sarracenia, Drosera, and Utricularia, and 
found that the protoplasm under the influence of the stimula- 
tion gains an increased power of imbibition. Water is with- 
drawn by it from the cell-sap, and in Sarracenia and Drosera 
the tannin with which the cell-sap is laden becomes concen- 
trated, and gives rise to the appearance Darwin called 
“ Aggregation.” 
De Vries? describes the movements thus: 
1. An increase in the rapidity and vigour of circulation in 
the peripheral layer of protoplasm. 
2. A division of the vacuole into several smaller vacuoles, 
which are each surrounded by part of the original vacuole 
wall. 
3. A very marked diminution of the volume of the vacuole, 
because some of its original constituents are expelled through 
the vacuole wall, and collect between this and the circulating 
protoplasm. The expelled fluid has, at least approximately, 
1 Schimper, A. J. W., “ Notizen iiber insektfressende Pflanzen,” ‘ Bot. 
Zeit.,’ 1882, Nos. 14 and 15. 
2 De Vries, H., “ Ueber die Aggregation im Protoplasma von Drosera 
rotundifolia,” ‘ Botanische Zeitung,’ 1886. 
