50 DROSERA ROTUNDIFOLIA. [Cuar. IIL. 
extremely small, yet well defined, but many of the cells con- 
tained, in addition, some brownish pulpy matter. In two 
cases of leaves heated to 145° (62°°7 Cent.), a few tentacles 
could be found with some of their cells containing a few minute 
spheres; whilst the other cells and other whole tentacles 
included only the brownish, disintegrated or pulpy matter. 
The fluid within the cells of the tentacles must be in an 
oxygenated condition, in order that the force or influence 
which induces aggregation should be transmitted at the 
proper rate from cell to cell. A plant, with its roots in 
water, was left for 45 m. in a vessel containing 122 fluid oz. 
of carbonic acid. A leaf from this plant, and, for comparison, 
one from a fresh plant, were both immersed for 1 hr. in a 
rather strong solution of carbonate of ammonia. They were 
then compared, and certainly there was much less aggregation 
in the leaf which had been subjected to the carbonic acid 
than in the other. Another plant was exposed in the same 
vessel for 2 hrs. to carbonic acid, and one of its leaves was 
then placed in a solution of one part of the carbonate to 437 
of water ; the glands were instantly blackened, showing that 
they had absorbed, and that their contents were aggregated ; 
but in the cells close beneath the glands there was no aggre- 
gation even after an interval of 3 hrs. After 4 hrs. 15 m. a 
few minute spheres of protoplasm were formed in these cells, 
but even after 5 hrs. 30 m. the aggregation did not extend 
down the pedicels for a length equal to that of the glands. 
After numberless trials with fresh leaves immersed in a 
solution of this strength, I have never seen the aggregating 
action transmitted at nearly so slow a rate. Another plant 
was left for 2 hrs. in carbonic acid, but was then exposed for 
20 m. to the open air, during which time the leaves, being of 
a red colour, would have absorbed some oxygen. One of 
them, as well as a fresh leaf for comparison, were now 
immersed in the same solution as before. The former were 
looked at repeatedly, and after an interval 65 m. a few 
spheres of protoplasm were first observed in the cells close 
beneath the glands, but only in two or three of the longer 
tentacles. After 3 hrs. the aggregation had travelled down 
the pedicels of a few of the tentacles for a length equal to 
that of the glands. On the other hand, in the fresh leaf 
similarly treated, aggregation was plain in many of the 
tentacles after 15 m.; after 65 m. it had extended down the 
pedicels for four, five, or more times the length of the glands ; 
