Natural History. 195 



rhents after the introduction of the plant, the two nearest leaves 

 became slightly wrinkled and bent, so as to become doubled. 

 When forcibly opened, they again returned to this position. After 

 some hours, the leaves began to droop, to twist ; they then be- 

 came flabby, and in twenty-four hours the plant was dead, all 

 the petioles being bent in the middle. This kind of poison 

 appears to act in animals on the spinal marrow, producing tetanus, 

 and then death. 



Prussic Acid. — A solution of this acid being used, the petioles 

 began to bend in three hours, and in about twelve hours the plant 

 was quite dead. All the petioles were as if broken in the middle. 



A drop or two of strong prussic acid, put on to the end of the- 

 leaf of a sensitive plant, caused several of the neighbouring 

 leaves to close in a few moments. A spoon containing prussic 

 acid or the open bottle being held near the leaves, caused them to 

 fade. In all these experiments the leaves experimented upon re- 

 gained their sensibility only after some hours. 



Laurel'tvater. — In a few moments many of the leaves became 

 wrinkled and rolled up, in about half an hour they opened, be- 

 came flabby, and in six or seven hours the plant was dead. The 

 wrinkling of the leaves varied considerably at different times. 



Belladonna. — A solution of five grains of the extract in one 

 ounce of water was used. In a few minutes the lower leaves 

 drooped a little, in the evening they had partly returned to the 

 natural state ; next morning, they and others had drooped ; on the 

 second day the leaves had begun to change colour ; on the fourth 

 day the plant was dead. 



Alcohol. — The alcohol was mixed with its volume of water ; the 

 plant died in twelve hours. The leaves had faded and were soft. 

 When weak alcohol, containing three grains of camphor in half 

 an ounce, was used, the plant died in twelve hours ; but, in addi- 

 tion to the above appearances, the petioles were bent as if broken 

 in the middle. 



Oxalic Acid. — Five grains of the acid were dissolved in one ounce 

 of water, and a rose branch put into it. In twenty- four hours 

 the rose began to fade, and in forty-eight hours the flower and 

 branch were both dead. The plant had absorbed only one grain 

 of liquid in the last twenty-four hours, and but the tenth of a 

 grain of oxalic acid had been taken up altogether. A bean plant 

 in a similar solution died in twenty-four hours. 



Hemlock. — Five grains of extract in one ounce of water. 

 Wrinkling of the lower leaves in a few minutes ; these leaves 

 dead in twenty-four hours ; the whole plant dead in forty-eight 

 hours. 



Digitalis. — Six grains of the substance in one ounce of water. 

 In a few moments some of the leaves became slightly Wrinkled at 



O 2 



