Cuar. II] THE PROCESS OF AGGREGATION. 35 
simpler and commonest changes. The cell A, when first 
sketched, included two oval masses of purple protoplasm 
touching each other. These became separate, as shown at B, 
and then reunited, as at C. After the next interval a very 
common appearance was presented—D, namely, the formation 
of an extremely minute sphere at one end of an elongated 
Fig. 8, 
(Drosera rotundifolia.) 
Diagram of the same cell of a tentacle, showing the various forms successively 
assumed by the aggregated masses of protoplasm. 
mass. 
This rapidly increased in size, as shown in E, and 
was then reabsorbed, as at F, by which time another sphere 
had been formed at the opposite end. 
The cell drawn in fig. 7 was from a tentacle of a dark red 
leaf, which had caught a small moth, and was examined 
certain alterations of form occurring 
in the above-mentioned body de- 
scribed by Gardiner under the name 
of rhabdoid, and which seems to be 
peculiarly sensitive to changes in 
the turgidity, so much so indeed that 
the author utilises it as a “turgo- 
meter,” or index of the degree of 
turgescence. 
H. de Vries has also written on 
the subject of aggregation (‘ Botan- 
ische Zeitung,’ 1886, p. 1), and his 
views agree with those of Pfeffer, 
Schimper, and Gardiner as to the 
main fact that the aggregated masses 
are concentrations of cell-sap. In 
some other respects they differ from 
the conclusions of these authors. 
De Vries believes that in Drosera 
and in vegetable cells generally the 
vacuoles are surrounded by a special 
protoplasmic wall, distinct from 
the layer of flowing protoplasm 
which lines the walls. In the 
process of aggregation the vacuole 
expels a great part of its watery 
contents, retaining, however, the 
red colouring matter of the cell- 
sap, as well as tannin and albu- 
minous matter. The vacuole does 
not remain a single body, but divides 
into numerous secondary vacuoles. 
These are the aggregated masses 
which are rendered conspicuous by 
being surrounded by, the expelled 
fluid which serves as a colourless 
background to them. The move- 
ments of the masses are, according to 
De Vries, entirely passive, and are 
accounted for by the currents of 
protoplasm, stirring them and wash- 
ing them to and fro—F. D.] 
D2 
