Cuar. IIL THE PROCESS OF AGGREUATION. 51 
which by the next morning, after 24 hrs., had almost dis- 
appeared, the leaf being evidently dead. Nor was there any true 
aggregation in leaves immersed in propionic acid of the same 
strength; but in this case the protoplasm was collected in 
irregular masses towards the bases of the lower cells of the 
tentacles. 
A filtered infusion of raw meat induces strong aggregation, 
but not very quickly. In one leaf thus immersed there was a 
little aggregation after 1 hr. 20 m., and in another after 1 hr. 
50 m. With other leaves a considerably longer time was re- 
quired: for instance, one immersed for 5 hrs. showed no aggre- 
gation, but was plainly acted on in 5 m., when placed in a few 
drops of a solution of one part of carbonate of ammonia to 146 
of water. Some leaves were left in the infusion for 24 hrs., 
and these became aggregated to a wonderful degree, so that 
the inflected tentacles presented to the naked eye a plainly 
mottled appearance. The little masses of purple protoplasm 
were generally oval or beaded, and not nearly so often spherical 
as in the case of leaves subjected to carbonate of ammonia. 
They underwent incessant changes of form; and the current of 
colourless protoplasm round the walls was conspicuously plain 
after an immersion of 25 hrs. Raw meat is too powerful a 
stimulant, and even small bits generally injure, and sometimes 
kill, the leaves to which they are given: the aggregated masses 
of protoplasm become dingy or almost colourless, and present 
an unusual granular appearance, as is likewise the case with 
leaves which have been immersed in a very strong solution of 
carbonate of ammonia. A leat placed in milk had the contents 
of its cells somewhat aggregated in 1 hr. Two other leaves, 
one immersed in human saliva for 2 hrs. 80 m., and another 
in unboiled white of egg for 1 hr. 30 m., were not acted on in 
this manner; though they undoubtedly would have been so, 
had more time been allowed. These same two leaves, on being 
afterwards placed in a solution of carbonate of ammonia (8 grs. 
to 1 oz.), had their cells aggregated, the one in 10 m. and the 
other in 5m. : 
Several leaves were left for 4 hrs. 30 m. in a solution of one 
part of white sugar to 146 of water, and no aggregation ensued 
on being placed in a solution of this same strength of carbonate 
of ammonia, they were acted on in 5m.; as was likewise a leaf 
which had been left for 1 hr. 45 m. in a moderately thick solu- 
tion of gum arabic. Several other leaves were immersed for 
some hours in denser solutions of sugar, gum, and starch, and 
they had the contents of their cells greatly aggregated. This 
