Cuar. XL GENERAL SUMMARY. 267 
of meat than they were before. If exposed to a tem- 
perature of between 115° and 125° (46°-1—51°6 Cent.). 
they are quickly inflected, and their protoplasm under- 
goes aggregation; when afterwards placed in cold water, 
they re-expand. Exposed to 130° (54°-4 Cent.), no in- 
flection immediately occurs, but the leaves are only 
temporarily paralysed, for on being left in cold water, 
they often become inflected and afterwards re-expand. 
In one leaf thus treated, I distinctly saw the protoplasm 
in movement. In other leaves, treated in the same 
manner, and then immersed in a solution of carbonate 
of ammonia, strong aggregation ensued. Leaves placed 
in cold water, after an exposure to so high a tem- 
perature as 145° (62°7 Cent.), sometimes become 
slightly, though slowly, inflected; and afterwards have 
the contents of their cells strongly aggregated by car- 
bonate of ammonia. But the duration of the immer- 
sion 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 albu- 
men, 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 con- 
siderably in their power of resisting heat. Unless the 
heat has been sufficient to coagulate the albumen, car- 
bonate 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 decoction of green peas or 
of fresh cabbage-leaves acts almost as powerfully as an 
infusion of raw meat; whereas an infusion of cabbage: 
