Chap. XI.] GENERAL SUMMARY. 217 



(54.4 Cent.), no inflection 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 pro- 

 toplasm 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 temperature as 

 145 (62.7 Cent.), sometimes become slightly, though 

 slowly inflected; and afterwards have the contents of their 

 cells strongly aggregated 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, thej' are killed, and the con- 

 tents 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 considerably in 

 their power of resisting heat. Unless the heat has been suf- 

 ficient to coagulate the albumen, carbonate of ammonia sub- 

 sequently induces aggregation. 



In the fifth chapter the results of placing drops of vari- 

 ous 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 al- 

 most 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 cab- 

 bage-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 diges- 

 tion, 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 vege- 

 table kingdom. It is likewise an interesting fact that the 

 glands of the disc, when irritated, should transmit some in- 



