Cuar. III. THE PROCESS OF AGGREGATION. 53 
Heat induces aggregation. A leaf, with the cells of the 
tentacles containing only homogeneous fluid, was waved about 
for 1m. in water at 180° Fahr. (54°4 Cent.), and was then 
examined under the microscope as quickly as possible, that 
is in 2 m. or 3 m.; and by this time the conjents of the 
cells had undergone some degree of aggregation. A second leaf 
was waved for 2m. in water at 125° (51°-6 Cent.) and quickly 
examined as before; the tentacles were well inflected; the 
purple fluid in all the cells had shrunk a little from the walls, 
and contained many oval and elongated masses of protoplasm, 
with a few minute spheres. A third leaf was left in water at 
125°, until it cooled, and when examined after 1 hr. 45 m., the 
inflected tentacles showed some aggregation, which became 
after 3 hrs. more strongly marked, but did not subsequently 
increase. Lastly, a leaf was waved for 1 m. in water at 120° 
(48°8 Cent.) and then left for 1 hr. 26 m.in cold water; the 
tentacles were but little inflected, and there was only here and 
there a trace of aggregation. In all these and other trials 
with warm water the protoplasm showed much less tendency 
to aggregate into spherical masses than when excited by car- 
bonate of ammonia. : 
Redissolution of the Aggregated Masses of Protoplasm.—As soon 
as tentacles which have clasped an insect or any inorganic 
object, or have been in any way excited, have fully re-expanded, 
the aggregated masses of protoplasm are redissolved and dis- 
appear; the cells being now refilled with homogeneous purple 
fluid as they were before the tentacles were inflected. The 
process of redissolution in all cases commences at the basts of the 
tentacles, and proceeds up them towards the glands. In old 
leaves, however, especially in those which have been several 
times in action, the protoplasm in the uppermost cells of the 
pedicels remains in a permanently-more or less aggregated con- 
dition. In order to observe the process of redissolution, the 
following observations were made: a leaf was left for 24 hrs. in 
a little solution of one part of carbonate of ammonia to 218 of 
water, and the protoplasm was as usual aggregated into number- 
less purple spheres, which were incessantly changing their 
forms. The leaf was then washed and placed in distilled water, 
and after 3 hrs. 15 m. some few of the spheres began to show by 
their less clearly defined edges signs of redissolution. After 
9 hrs. many of them had become elongated, and the surround- 
ing fluid in the cells was slightly more coloured, showing 
plainly that redissolution had commenced. After 24 hrs., 
though many cells still contained spheres, here and there one 
