Chap. III. THE PKUCESS 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 iii 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 oz.), so that each leaf received -^ of a grain (-1124 mgr.). 

 This quantity caused all the tentacles to be inflected, but after 

 24 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 hrs.; but in the other 

 there was a trace of aggregation after 52 m., and' this was 

 plainly marked after 1 hr. 22 m., but even after 2 hrs. 12 m. 

 there was certainly not more aggregation than would have fol- 



