THE FUNCTIONS OF ROOT-HAIRS. 55 



emphatically so, attack the position that such 

 analyses alone can explain the problems of 

 agriculture. 



On the other hand, we rriust not rest satisfied 

 with the suggestions so far put forward to account 

 for the processes referred to, since it is impossible 

 to overlook the fact that in their present form 

 they merely afford proximate explanations, and 

 and are too crudely mechanical for finality. 



Notes on Chapter VI. 



In addition to the works referred to in the last chapter, the 

 student should consult Pfeffer's Physiology, pp. 86-149, and 

 pp. 410-441. With reference to water cultures, Sachs' 

 Lectures, XVII., may also be consulted. The standard work 

 on ash constituents of plants is Wolff, Aschen-analysen, 187 1 

 and 1880, an indispensable book of reference in this con- 

 nection, though there are others, quoted in Pfefifer, where 

 further hterature may also be found. 



