58 



Of later experiments there need be mentioned 

 specifically only the work of Ebermayer 1 , lau.2 and Rus- 

 sell and Appleyard 3 . The results of these investigators 

 show that the percentage of carbon dioxide is higher 

 in plant-covered soils than in bare soils, and, in 

 general, is higher in cultivated soils than in unculti- 

 vated ones. It is also higher in summer than in winter. 

 Much other data which need not be cited in detail is 

 essentially confirmatory of the conclusions already stated 4 . 



1. Forsch. Geb. Agr. Phys. 13: 15-4* (1890). 



2. Diss., Rostock, 1906. 



3. Jour. Agr. Sci. ]_: 1-45 (1915). 



4. For this data see: Peters,- Landw. Vers. 

 Stat. 4: 133 (186E); Schlosing,- G. R. _77: 203 (1873); 

 Ebermayer,- Forsch. Geb. Agr. Physik 1: 159 (1878), 3: 



1 (1880); Moller,- I.litteil. forstl. Versuchswesen Oesterr. 

 2: 121 (1878), Porsch. Geb. Agr. Physik. 2: 329 (1879); 

 Wollny,- Landw. Vers. Stat. 25: 373-391 (1880), Porsch. 

 Geb. Agr. Physik 3: 8 (1880), 9_: 185 (1886), 12: 385 

 (1889), 13: 143 (1890), 19: 151-171 (1896); Sachsse,- 

 Lahrb. Agriculturchem. , p. 142 (1888); Schloessing,- 

 G. R. 109 : 618-620, 673-676 (1889); Deherain,- Ann. Agron. 

 22: 44y-469 (1896); Belz, in Buckingham,- U. S. Bur. 

 Soils, Bull._25, p. 3* (1904); Stoklasa and Ernest, - 

 Gentbl. Bakt., Abt. 2, 14: 723-736 (1905), Zeits. Zuckering 

 Bo'hmen 31: 291-307 (1907); Vafceler,- Mitth. Kgl. Bayer- 

 ischen Moorkulturanstalt 1: 30 (1907); Barakov,- Zhur. 



