564 



Miscellaneous. 



the obstinate and ignorant vegetable physiologists who shew such 

 disinclination to feed on the riches afforded them by chemistry. 



Next comes " the assimilation of nitrogen," in which nothing 

 material is found, with the exception of the new researches of Bous- 

 singault. This is the only subject of which physiology has not yet 

 made use. Before Boussingault's researches, both physiologists and 

 chemists, Dr. Liebig included, were ignorant of the true origin of 

 nitrogen in plants ; and since those researches have been published, 

 no work on physiology has been printed. 



Then follows a chapter on the *' inorganic constituents of vegeta- 

 tion" (p. 85). Here we first have a number of known facts, proving 

 the existence of salts in plants, and next a view, which, indeed, 

 is very ingenious, and which, if pursued, cannot fail to excite great 

 interest. From the analysis of the ashes of two kinds of fir-wood, 

 made by Saussure, and of two kinds of pine- wood, made by Berthier, 

 Dr. Liebig draws the conclusion that every species of plants absorbs 

 from the soil a certain quantity of alkaline bases, containing an in- 

 variable proportion of oxygen, in order to saturate a quantity of ve- 

 getable acid, likewise constant, which is produced by the process of 

 vegetation. This idea strikes the mind forcibly, and certainly de- 

 serves to be investigated by exact and very comprehensive analyses. 

 But unhappily for Dr. Liebig, he soon afterwards states, that 

 in Lichens oxalate of lime is to be considered as a substitute for 

 the woody fibre, which is absent. It is hardly possible to keep one's 

 temper in speaking of such nonsense. Woody fibre consists of 

 elongated tubes, and oxalate of lime occurs only within cells, which 

 are usually of a roundish shape ; and it occurs moreover not only in 

 Lichens, but also in other plants, as in many Cacti, which contain as 

 much as 85 per cent, of this matter ; a much larger quantity than is 

 found in any kind of Lichen. This fact is known to every chemist's 

 apprentice, who has attended lectures on botany. I must leave the 

 reader to discover the value of Dr. Liebig's speculation. Our author 

 (at p. 74,) asserts, that it can be easily proved that animal manure 

 aflfects the growth of plants only by forming ammonia ; but (at p. 

 98) he forgets what he said before, and attributes the advantageous 

 effects of cow-dung on the banks of the Rhine to the potash it 



