110 BIOLOGY. [Book ii 



being decomposed to oxydize these matters, and a part of iti 

 hydrogen combines itself with the azote of the air and formi 

 ammonia. Plants raised in ulmic acid and powdered charcoal, 

 entirely deprived of ammonia, shut up in an atmosphere and 

 watered with water which was also destitute of it, have yielded 

 to analysis a double or treble quantity of azote to that which 

 their seed contained at the commencement of the experiment. 

 In this case, the plant being deprived of ammonia, it is very 

 possible that it had absorbed the azote directly from the air. 

 The following facts render this a very probable eventuality : — 



Schroeder sowed cereals in flower of sulphur watered with 

 distilled water, and contained in vessels of glass or porcelain 

 covered with a receiver. The seeds germinated, and produced 

 halms from 2 to 14 inches in length, bearing short ears, which 

 however flowered. When dried, they were five times the weight 

 of those seeds from which they sprang. 



Boussingault sowed twenty-nine seeds of clover in sand 

 previously reddened in the fire. The plants which they produced 

 weighed 67 grains at the end of three months. {Annales de 

 Ghimie, t. Ixxvii.) 



Peas treated in the same way jaelded in. the same space of 

 time plants weighing 72 grains, loaded with flowers and perfect 

 seeds, &c. (Quoted by Burdach, Traite de Physiologie, t. ix. p. 

 255.) Finally, as we shall see further on, recent experiments of 

 M. G. Ville put the normal absorption of atmospheric azote by 

 the plant almost beyond doubt. 



If the anatomical elements of plants bring about many 

 chemical syntheses, they are also very capable of disaggregating 

 mineral compounds. We know that chlorophyll decomposes the 

 carbonic acid of the air. It has been also observed, that seeds 

 germinating in water decompose it, and absorb a portion of its 

 hydrogen. 



The oxygen contained in a plant comes in a large, degree from 

 the aerian medium ; a notable portion of it from the decomposi- 

 tion of the carbonic acid by chlorophyll. The plant also 



