Cuar. IIL THE PRUCESS OF AGGREGATION. 49 
146 of water, and were acted on quite as energetically, but 
perhaps not quite so quickly, as by the carbonate. After 10 m. 
the glands were black, and in the cells beneath them there were 
traces of aggregation, which after 15 m. was well marked, extend- 
ing down the tentacles for a length equal to that of the glands. 
After 2 hrs. the contents of almost all the cells in all the ten- 
tacles were broken up into masses of protoplasm. A leaf was 
immersed in a solution of one part of oxalate of ammonia to 
146 of water; and after 24 m. some, but not a conspicuous, 
change could be seen within the cells beneath the glands. 
After 47 m. plenty of spherical masses of protoplasm were 
formed, and these extended down the tentacles for about the 
length of the glands. This salt, therefore, does not act so 
quickly as the carbonate. With respect to the citrate of am- 
monia, a leaf was placed in a little solution of the above 
strength, and there was not even a trace of aggregation in the 
cells beneath the glands, until 56 m. had elapsed; but it was 
well marked after 2 hrs. 20 m. On another occasion a leaf 
was placed in a stronger solution, of one part of the citrate to 
109 of water (4 grs. to 1 oz.), and at the same time another 
leaf in a solution of the carbonate of the same strength. The 
glands of the latter were blackened in less than 2 m., and 
after 1 hr. 45 m. the aggregated masses, which were spherical 
and very dark-coloured, extended down all the tentacles, for 
between half and two-thirds of their lengths; whereas in the 
leaf immersed in the citrate the glands, after’30 m., were of 
a dark red, and the aggregated masses in the cells beneath them 
pink and elongated. After 1 hr. 45 m. these masses extended. 
down for only about one-fifth or one-fourth of the length of the 
tentacles. 
Two leaves were placed, each in ten minims of a solution of 
one part of nitrate of ammonia to 5250 of water (1 gr. to 
12 02.), so that each leaf received 54; of a grain (*1124 mgr.). 
This quantity caused all the tentacles to be inflected, but after 
94 hrs. there was only a trace of aggregation. One of these 
same leaves was then placed in a weak solution of the car- 
bonate, and after 1 hr. 45 m. the tentacles for half their lengths 
showed an astonishing degree of aggregation. Two other 
leaves were then placed in a much stronger solution of one part 
of the nitrate to 146 of water (3 grs. to 1 oz.); in one of these 
there was no marked change after 3 brs.; but in the other 
there was a trace of aggregation after 52 m., and this was 
plainly marked after 1 hr. 22m, but even after 2 hrs. 12 m. 
there was certainly not more aggregation than would have fol- 
