ABSORPTION OF WATER. Ji 



27. Can plants absorb minerals in solution in water through 

 the roots? 



Answer by Experiment 13. 



EXPERIMENT 13. This maybe tested by comparing the growth 

 of seedlings in \vater containing minerals, with the growth of those 

 in water lacking them. Prepare two germinators as follows: Take 

 two common tumblers with sloping sides, and make rings of wire or 

 glass tubing of such a size that they may be supported by wire or 

 tubing inside and about half-way up the tumblers. Sew tightly over 

 these rings pieces of cheese-cloth which hang to the bottom of the 

 tumblers. Fill one to near the ring with distilled water, and another 

 to the same height with nutrient solution. Sow about twenty radish 

 or mustard seeds on each cloth, and observe the comparative rate of 

 growth. Place black paper around the bottoms of the tumblers to 

 keep the roots in their natural darkness and to prevent the develop- 

 ment of Algae in the nutrient solution (see Fig. 13). 



FIG. 13. SIMPLE WATER-CULTURE VESSELS. 

 One-third the true size. 



(Cheese-cloth sometimes does not absorb water readily, in which case 

 it may be helped by thorough boiling ; or instead of it, thin sheets of 

 cotton batti)ig may be used to advantage.} 



A better method of supporting the cheese-cloth is to cut the inside 

 from corks, making floating rings a little smaller than the diameter of 

 the tumbler ; or, still better are rings of an inch in depth turned from 

 pine on a lathe. 



The nutrient solution is to be made up from one of the formulae com- 

 monly given in physiological works, as for instance Detmer, ?, 3 ; Good- 



