216 DROSERA ROTUNDIFOLIA. (Cmar. XI. 
then immersed in a solution of carbonate of ammonia, strong 
aggregation ensued. Leaves placed in cold water, after an 
exposure to so high a temperature as 145° (62°-7 Cent. ), 
sometimes become slightly, though slowly inflected; and 
afterwards have the contents of their cells strongly aggre- 
gated by carbonate of ammonia. But the duration of the 
immersion is an important element, for if left in water at 145° 
(62°-7 Cent.), or only at 140° (60° Cent.), until it becomes cool, 
they are killed, and the contents of the glands are rendered 
white and opaque. This latter result seems to be due to the 
coagulation of the albumen, and was almost always caused 
by even a short exposure to 150° (65°°5 Cent.) ; but different 
leaves, and even the separate cells in the same tentacle, 
differ considerably in their power of resisting heat. Unless 
the heat has been sufficient to coagulate the albumen, 
carbonate of ammonia subsequently induces aggregation. 
In the fifth chapter, the results of placing drops of various 
nitrogenous and non-nitrogenous organic fluids on the discs 
of leaves were given, and it was shown that they detect with 
almost unerring certainty the presence of nitrogen. A de- 
coction of green peas or of fresh cabbage-leaves acts almost 
as powerfully as an infusion of raw meat, whereas an infusion 
of cabbage-leaves made by keeping them for a long time in 
merely warm water is far less efficient. A decoction of grass- 
leaves is less powerful than one of green peas or cabbage- 
leaves. 
These results led me to inquire whether Drosera possessed 
the power of dissolving solid animal matter. The experi- 
ments proving that the leaves are capable of true digestion, 
and that the glands absorb the digested matter, are given in 
detail in the sixth chapter. These are, perhaps, the most 
interesting of all my observations on Drosera, as no such 
power was before distinctly known to exist in the vegetable 
kingdom. It is likewise an interesting fact that the glands 
of the disc, when irritated, should transmit some influence 
to the glands of the exterior tentacles, causing them to se- 
crete more copiously and the secretion to become acid, as if 
they had been directly excited by an object placed on them. 
The gastric juice of animals contains, as is well known, an 
acid and a ferment, both of which are indispensable for diges- 
tion, and so it is with the secretion of Drosera. When the 
stomach of an animal is mechanically irritated, it secretes an 
acid, and when particles of glass or other such objects were 
