196 Miscellaneous Intelligence* 



the extremity, in the evening these extremities were dead, and 

 twenty-four hours after the whole plant was dead. 



From the whole of these experiments, M. Marcet concludes, 1. 

 That metallic poisons act upon vegetables nearly as they do upon 

 animals. They appear to be absorbed and carried into different 

 parts of the plant, altering and destroying the vessels by their 

 corrosive powers. 2. That vegetable poisons, especially those 

 which have been proved to destroy animals by their action on the 

 nervous system, also cause the death of plants. But as it cannot 

 be supposed that poisons, which do not attack the organic structure 

 of animals, should affect that of vegetables, so as to kill them in 

 a few hours, it appears very probable that there exist in the latter 

 a system of organs which is affected by poisons nearly as the 

 nervous system of animals. 



Then follow some experiments on the action of certain gases 

 on the roots of plants. It is known that if a plant be taken 

 from the earth, and its roots be introduced into a receiver of at- 

 mospheric air, containing moisture, whilst the leaves are in the 

 air above the receiver, there will be found after some hours a 

 small quantity of carbonic acid gas. This has generally been 

 supposed to be formed by the combination of the oxygen of the 

 air with the excess of carbon in the roots. In the following ex- 

 periments the roots were placed in different gases, that it might 

 be ascertained whether when no oxygen was present, and when 

 therefore no carbonic acid should be formed, the plant died more 

 suddenly. Six similar bean plants were selected and fixed into 

 receivers placed over water, so that moisture should be present in 

 the gases, the apertures by which the stems passed out being 

 closed carefully. Different gases were then introduced into the 

 receivers, and the following results obtained. 



i. Atmospheric air. — The plant remained healthy for forty-eight 

 hours, and then gradually faded. 



ii. Hydrogen. — The plant began to fade in five or six hours, 

 and was quite dead in fourteen or sixteen hours. The leaves 

 were faded and the stem bent. 



iii. Carbonic acid. — The plant began to fade in two hours, and 

 was dead in eight or ten hours. All the leaves were faded, and 

 the stem bent in the middle. 



iv. Nitric oxide. — The leaves began to bend in about six hours, 

 and the plant did not die in less than twelve hours. It appears 

 not impossible that a little carbonic acid may have here been 

 formed, the nitric oxide being readily decomposable. 



v. Nitrogen. — The leaves began to droop almost immediately ; 

 in three hours the skin and upper leaves were bent and faded, 

 and in five hours all the leaves were faded, and the plant dead. 

 This gas seems most injurious of all those tried. — Ann, de Chim.y 

 xxix. 200, 



