22 



oxygen or that good soil aeration is the uniformly neces- 

 sary factor it is commonly supposed to be. The ex- 

 perimental part of this paper will show that the 

 theoretical possibility of anaerobic root existence ap- 

 pears to have been realized in one case at least. 



The complex and multiform aerating systems found 

 in the aerial portions of many plants have little impor- 

 tance for the present inquiry. In the case of green 

 plants it is probable that these systems are occupied 

 more with the supply of the carbon dioxide used in 

 photosynthesis^ than with the supply of oxygen for respira- 



1. On these systems see: Unger,- Sitzungsber. 

 Akad. Wiss. Wien 12 : 367 (1854); Bufour,- Arb. V/urzburg 

 3: 37 (1887); Goebel,- Bot. Ztg. 45: 717 (1887); Devaux,- 

 Rev. gen. Bot. 3: 49 (1891), Ann. Sci. nat. (8) 12: 221 

 (1900); Aubert,- Rev. gen. Bot, 4: 276 (1892); Pappen- 

 heim,- Bot. Gentbl. 49: 36 (1892); Bonnier,- Rev. gen. 

 Bot, 5: 111 (1893); Hunter,- Ann. Bot. 29: 627-634 (1914), 

 Farther literature is cited by Pfeffer,- Physiology of 

 Plants, vol. 1, pp. 176-206 (1900) and Haberlandt,- 

 Physiological Plant Anatomy, pp. 432-484 (1914). 



2. For instance Stahl has found the aerating 

 system better developed when plants are grown in strong 

 light. ftber den sonnigen und schattigen Standorts auf 

 der Ausbildung der laubblatter, 1883, p. 17. On the entry 

 of carbon dioxide into the aerating systems see the classi- 

 cal investigations of Brown and Escomb,- Phil. ^rans. 193: 

 223-292 (1900), Proc. Roy. Soc. 70; 397-413 (1902). 



