Cur. UI. THE PROCESS 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 Dionza, 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 
