CHAP. III. THE PEOCESS OF AGGREGATION. 57 



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 sensi- 

 tive filaments of Dionasa, which do not secrete, like- 

 wise 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 oxygenated condition for the transmission of the 

 process at the proper rate. Some tentacles in a 

 drop 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 almost 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 not been 

 completely emptied of their contents. Though I 

 looked carefully, no signs of a current could be seen 

 within these ruptured cells. They had evidently been 

 killed by the pressure ; and the matter which they 



