CIAI EVIDENCE OF THE NEED 01 ROOTS - B - E . 



It was mentioned in the introduction that the 

 customary assumption of the need for soil aeration rests 

 on inferential evidence of three kinds: t physiological 

 (the necessity of oxygen for protoplasm^ respiration) , 

 morphological (the aerating systems of plants), and cul- 

 tural (the agricultural benefit and ecological significance 

 of good soil aeration). This inferential evidence must 

 he examined a little more in detail; as also the existing 

 facts which have contrary implications. 



The general existence of, and need for, proto- 

 plasmic respiration of the usual character is too well 

 known to require review. 1 Hearty all experiments, how- 

 ever, have been made on entire plants or on their aerial 

 portions or else on free-living plants such as algae or 

 bacteria. Experiments on tmrni. respiration^ have been con- 



fined largely to work with beets, potatoes and similar 



H 3ee the summaries of Palladin,- I'flansen- 

 physiologie, pp. 179-211 (1911) and Bayliss,- Principles 

 of General Physiology, pp. 580-63C (1915), also Vernon- 

 Biochemistry of Respiration,- Science Prog, 9_: 251-269 

 (1914). 



