872 INFLUENCE OF VEGETATION IN 



motion. But a still more remarkable difference 

 between them is, that plants have the faculty of 

 converting the binary constituents of inorganic 

 matter, such as water, carbonic acid, and perhaps 

 ammonia, into their own substance, by a peculiar 

 species of action, intermediate between ordinary 

 chemistry and that of animal bodies: whereas 

 the latter cannot be nourished except by plants 

 that have been already organized, or by other 

 animals that have been ultimately nourished by 

 plants. It is therefore evident that as animals 

 have no means of assimilating inorganic matter, 

 they could not exist without plants. 



On the other hand, it has been wisely ordained, 

 that those substances, which are rejected by ani- 

 mals as excrementitious and injurious, are the 

 appropriate food of vegetation. And it would 



which have no leaves for decomposing carbonic acid, have no 

 visible organs of circulation, secretion, or reproduction, and con- 

 sist chiefly of a simple homogeneous, cellular tissue. It may also 

 be observed here, that the lowest species of animals, which have 

 no specific organs of respiration, have neither heart, brain, nerves, 

 muscles, nor blood ; and consist chiefly of a gelatinous mass, such 

 as the medusa, polypus, echinus, sponge, and other zoophytes, 

 which are scarcely to be distinguished from plants. M. Bec- 

 querel observes in a lecture delivered before the Academy of 

 Sciences at Paris, on the 13th of July 1840, that plants have a 

 temperature of their own, though very different from that of the 

 surrounding media, but that it is inappreciable during the night, 

 on account of their sleep, and shows itself under the influence of 

 light. Query : might not the difference of temperature between 

 day and night explain the phenomenon quite as well as the sup- 

 posed influence of sleep ? 



