19 



and the presence of which is responsible for the pro- 

 duction of an "acid" or "sour" soil which is conse- 

 quently infertile. 1 These toxins are probably £he in- 

 termediate products of the partial respiration which 



1. On acid excretions by roots in the presence 

 of insufficient oxygen see especially: Stoklasa and 

 Ernest,- Jahrb. wiss. Bot. 46: 55-102 (1908), also: 

 Stiehr,- Inaug. Diss., Kiel, 1903; Schreiner and Reed,- 

 Bull. Torrey Bot. Club, 34: 279-303 (1907); Schleichert,- 

 Naturw. Wochenschr. 22: 91-94 (1907); Heed,- Pop. 3ci. 

 Mon. 73: 257-266 (1908). On dihydroxy stearic acid, a 

 particular toxin found in badly aerated soils see: 

 Schreiner and Shorey,- U. 8. Bureau of Soils, Bull. 53 , 

 53 pp., 1909; Schreiner and Skinner,- U. S. Bureau of 

 Soils, Bull. 70, 98 pp., 1910; Schreiner and Lathrop,- 

 Jour. Amer. Chem. Soc. 33: 1412-1417 (1911). On "sour" 

 soils in general see Cameron,- The Soil Solution, pp. 

 (1912), and Russel,- Soil Conditions and Plant Growth, 

 2nd ed. , pp. 113-116 (1915) and literature cited by 

 these authors. On the toxins of bog waters and soils 

 seei Livingston,- Bot. Gaz. 37: 383-385 (1904), 3y_: 

 348-355 (1905); Dachnowski,- Bot. Gaz. 46: 130-143 (1908), 

 47: 389-405 (1909), 54: 503-514 (1912), Bull. Torrey 

 Bot. Club 39: 53-62 (1912); Jodidi,- :iich. Agr. Exp. 

 Sta., Tech. Bull. 4, 1909; Bauman and Gully,- Ilitth. K. 

 Bayr. Lloorkulturanst. 4: 31-56 (1910; Bottomley,- Ann. 

 Bot. 28: 531-540 (lyl4). Other literature is reviewed 

 by Rigg,- Plant World, 19: 310-325 (1916). 



