60 



soil. 1 These processes go on together, henoe when 

 carbon dioxide is high oxygen is low. Production of 

 carbon dioxide and its content in the soil air is great- 

 est at those times and places when and where conditions 

 are jnost favorable to vital activity. Carbon dioxide 

 ^» unA deep in the soil diffuses out more slowly, hence 

 its percentage is higher there than in the upper layers. 



In the light of the probable production of 

 carbon dioxide and consumption of oxygen in the deeper 

 soil layers, and of the relative slowness with which 

 outward diffusion must remove the one and renew the 

 other, it is a little surprising that the analyses of 



1. Schlosing and Muntz,- C. H. 84: 301, 65: 

 1018 (1877J; Smolenski,- Zeits. fur Biol. 13: 383 (1677); 

 Wollny,- Jour. Landw. 34: 213 (1886 J, Forsch. Geb. Agr. 

 Physik 13: 143 (1890), Zersetzung organ. Stoffe, p. 122 

 (1897); Ebermayer,- Porsch. Geb. Agr. Physik 13: 41 

 (1890); Liagnin,- Ann. sci. agron. Zj_ 1-68 (1896); Liarr,- 

 Meded. Proefstat. Oost-Java (4) 38: 503-542 (1908); 

 Stoklasa,- Zeits Landw. Versuchsw. Oesterr. 14: 1243- 

 1279 (1911); Hutchinson,- Report Agr. Res. Inst., Pusa 

 (India) 1911-1912 : 78-83; Haselhoff,- Landw. Jahrb. 

 47: 345-369 (1914); Shrenberg,- Bodenkolloide, pp. 515- 

 517 (1915). On the exoretion of carbon dioxide by the 

 roots of higher plants see literature cited on page f 

 note / . 



