50 DROSERA ROTUNDIFOLIA. Cuap. IIL 
lowed from an immersion of from 5 m. to 10 m. in an cqually 
strong solution of the carbonate. ; 
Lastly, a leaf was placed in thirty minims of a solution of 
one part of phosphate of ammonia to 43,750 of water (1 gr. to 
100 oz.), so that it received zJoq of a grain (04079 megr.); this 
soon caused the tentacles to be strongly inflected; and after 
94 hrs. the contents of the cells were aggregated into oval 
and irregularly globular masses, with a conspicuous current of 
protoplasm flowing round the walls. But after so long an 
interval aggregation would have ensued, whatever had caused 
inflection. 
Only a few other salts, besides those of ammonia, were tried 
in relation to the process of aggregation. A leaf was placed in 
a solution of one part of chloride of sodium to 218 of water, and 
after 1 hr. the contents of the cells were aggregated into small, 
irregularly globular, brownish masses; these after 2 hrs. were 
almost disintegrated and pulpy. It was evident that the proto- 
plasm had been injuriously affected; and soon afterwards some 
of the cells appeared quite empty. These effects differ alto- 
gether from those produced by the several salts of ammonia, 
as well as by various organic fluids, and by inorganic particles 
placed on the glands. A solution of the same strength of car- 
bonate of soda and carbonate of potash acted in nearly the same 
manner as the chloride; and here again, after 2 hrs. 30 m., the 
outer cells of some of the glands had emptied themselves of 
their brown pulpy contents. We shall see in the eighth 
chapter that solutions of several salts of soda of half the above 
strength cause inflection, but do not injure the leaves. Weak 
solutions of sulphate of quinine, of nicotine, camphor, poison of 
the cobra, &c., soon induce well-marked aggregation; whereas 
certain other substances (for instance, a solution of curare) 
have no such tendency. 
Many acids, though much diluted, are poisonous; and though, 
as will be shown in the eighth chapter, they cause the ten- 
tacles to bend, they do not excite true aggregation. Thus leaves 
were placed in a solution of one part of benzoic acid to 437 of 
water; and in 15m. the purple fluid within the cells had shrunk 
a little from the walls, yet when carefully examined after 1 hr. 
20 m., there was no true aggregation; and after 24 hrs. the leaf 
was evidently dead. Other-leaves in iodic acid, diluted to the 
same degree, showed after 2 hrs. 15 m. the same shrunken 
appearance of the purple fluid within the cells; and these, 
after 6 hrs. 15 m., were seen under a high power to be filled 
with excessively minute spheres of dull reddish protoplasm, 
