Chap. III.] THE PROCESS OF AGGREGATION. 49 



probable is it that water at a temperature of from 125 to 

 130 Fahr. (51.6 to 54.4 Cent.) should cause fluid to 

 pass, not only from the glands, but from all the cells of 

 the tentacles down to their bases, so quickly that aggregation 

 is induced within 2 m. or 3 m. Another strong argument 

 against this view is, that after complete aggregation, the 

 spheres and oval masses of protoplasm float about in an 

 abundant supply of thin, colourless fluid; so that at least 

 the latter stages of the process cannot be due to the want 

 of fluid to hold the protoplasm in solution. There is still 

 stronger evidence that aggregation is independent of se- 

 cretion; for the papillae, described in the first chapter, with 

 which the leaves are studded are not glandular, and do not 

 secrete, yet they rapidly absorb carbonate of ammonia or 

 an infusion of raw meat, and their contents then quickly 

 undergo aggregation, which afterwards spreads into the 

 cells of the surrounding tissues. We shall hereafter see 

 that the purple fluid within the sensitive filaments of Di- 

 onsea, which do not secrete, likewise undergoes aggregation 

 from the action of a weak solution of carbonate of ammonia. 

 The process of aggregation is a vital one; by which I 

 mean that the contents of the cells must be alive and 

 uninjured to be thus affected, and they must be in an oxy- 

 genated condition for the transmission of the process at 

 the proper rate. Some tentacles in a dfop of water were 

 strongly pressed beneath a slip of glass; many of the cells 

 were ruptured, and pulpy matter of a purple colour, with 

 ^granules of all sizes and shapes, exuded, but hardly any of 

 the cells were completely emptied. I then added a minute 

 drop of a solution of one part of carbonate of ammonia to 

 109 of water, and after 1 hr. examined the specimens. Here 

 and there a few cells, both in the glands and in the pedicels, 

 had escaped being ruptured, and their contents were well 

 aggregated into spheres which were constantly changing 

 their forms and positions, and a current could still be seen 

 flowing along the walls; so that the protoplasm was alive. 

 On the other hand, the exuded matter, which was now al- 

 most colourless instead of being purple, did not exhibit a 

 trace of aggregation. Nor was there a trace in the many 

 cells which were ruptured, but which had been completely 

 emptied of their contents. Though I looked carefully, no 



