H. BOTANY AND HORTICULTURE. 345 



season, from an atmosphere poor in ammonia; second, that 

 this absorption of ammonia, although relatively slight, is yet 

 incomparably greater than the power of absorption of a sur- 

 face of water for the ammonia contained in the atmosphere, 

 and also incomparably greater than that of moist quartz; 

 third, if the brown combinations are mixed in ascending pro- 

 portions, without quartz, so that the former constitute 1,3, 

 and 5 per cent, of the weight of the latter, the moist mix- 

 tures of the same surface have a disproportionately great 

 power of absorption for the ammonia of the atmosphere in a 

 dry season, and increasing more than proportionally with an 

 increasing amount of ulmin. 22 C, August, 1871, 130. 



EFFECT OF GERMINATION ON THE FAT IN SEEDS. 



In a paper read before the Academy of Sciences, at Munich, 

 by Dr. Vogel, upon the influence of the germination process 

 on the fat contained in seeds, it is stated that this decreases 

 in the ratio of from 0.094 to 0.320 per cent., or an average of 

 0.156 per cent. 1 A, December 8, 1871, 277. 



SOURCE OF NITROGEN IN PLANTS. 



It is well known that the quantity of nitrogen contained 

 in the crops exceeds in enormous proportion that existing in 

 the manures, the excess undoubtedly being derived from the 

 air. It is now a question whether this is extracted directly 

 from the air by plants, which would thus have the power of 

 assimilating directly, or if it is first taken from the air by the 

 soil, so as to combine with organic matter, and form an as- 

 similable compound. According to Deherain, oxygen, in the 

 presence of organic matter, combines directly with nitrogen 

 to form a compound analogous to the humus of the earth or 

 to ulmic acid. To illustrate this, he placed in a tube oxygen, 

 nitrogen, glucose, and ammonia. On drying the tube and 

 heating it, a black nitrogenized matter was left, and a portion 

 of the nitrogen in the tube w r as found to have disappeared. 

 ZB, December 14, 1871,600. 



ABSORPTION OF NITROGEN BY PLANTS. 



Dr. Cameron, in referring to certain experiments of Wag- 

 ner, in which it was ascertained that maize grew and devel- 

 oped seeds in a solution in which kreatine was the only ni- 



P2 



