246 I'llYTONOMY. 



been taken into the plant. It is also evident from the fact, that 

 lime, in combination with sulphuric acid, as we find it in gyp- 

 sum and marl, properly connnunicates no fertility to the soil, 

 but only a stimulating power ; on which account, marl, as a 

 manure, must always be interchanged by animal manure, if 

 we would not render the soil altogether barren ; (Mogehn- 

 sche Annalen). Free acids in the soil, especially when the 

 latter stands commonly under water, are rather hurtful to 

 vegetation, since the extractive matter of vsuch soils is not dis- 

 solved ; (Thaer, Grundsatze der rationellen Landwirth- 

 schaft). On this account, the mud which is taken from 

 streams and pools, must first be mixed with lime, if we would 

 assist by it the fertility of the soil. 



375. 



Experiments have shewn that the other stimulants act upon 

 plants as well as on animal bodies. Arsenic destroys the ir- 

 ritability of plants and germinating power of seeds. Opium, 

 too, acts on plants, although in a different manner from the 

 poisonous body we have last mentioned, which exalts the sus- 

 ceptibility to an extreme degree, but entirely destroys the 

 power of action. Opium, on the contrary, exhausts the sus- 

 ceptibility, by increasing the active power. Cherry-laurel 

 water, and Ticunas poison, bring plants speedily to a state of 

 decay, and take from them their irritability. 



Hydrogen gas seems, on the contrary, to act less injuriously 

 on plants than on animals, as it has also been found, that 

 plants with juicy and green leaves live entirely uninjured in 

 azotic gas, and exhale carbonic acid gas. But they die when 

 we take from them, by means of lime water, the carbonic 

 acid gas, which seems to be constantly changed by them into 

 a source of nourishment. 



II. Other Proofs of the Higher Lrf'c of Plants, 



Brugmans et Coulon, de mutata humoruin in regno orgamco indole a vi vi- 

 tali \asorum derivanda. 



Carradori Sulla Vitalita delle Piantc. 



G. Bell, in Memoirs of the Society of Manchester. 



