They also consider transpiration necessary to secure a 

 proper concentration of those salts, 



Pfeffer (9) regards transpiration essential for the 

 distribution of mineral salts in the plant and even main- 

 tains that growth varies 77ith the transpiration. He also 

 thinlcs it probable that transpiration influences the ex- 

 change of gases. If it were not for transpiration, the 

 Intercellular spaces ^vould become filled with water which 

 would prevent aeration of the tissues thus retarding meta- 

 bolism and growth. On the other hand, in the presence of 

 a limited supply of water in the plant, the diminution of 

 transpiration must of necessity interfere with the free ex- 

 change of gases thus inhibiting the assimilation of CQ3. 



Sachs (10) in commenting upon the fact that assimila- 

 tion may be carried on in land plants which are surrounded 

 by a saturated atmosphere, points out that the assimilation 

 in this case is extremely feeble and furthermore that even 

 under these conditions transpiration may occtir to a slight 

 degree and a feeble flow of water maintained. 



Edmond Gain (2) concludes from the works of Hellriegel 

 Haberlandt, Wollny and others that a certain relation 



