PHYSIOLOGICAL PROCESSES IN PLANTS 81 



5. What sort of soil permits of the most rapid evaporation 

 of water? 



6. What is the main cause of many million dollars worth of 

 expense to the governments and cities in dredging out and repair- 

 ing harbors? How might much of this expense be saved ? 



7. What is the main cause of dry springs and wells in 

 many districts ? 



8. Why is it important that the regions of the sources of 

 streams and rivers be forest clad ? 



9. What is the main cause of many disastrous floods and 

 freshets ? 



d. Necessity for Organic Matter 



Method. Fill three pots, one with clay subsoil, the second 

 with fertilizer, and the third with humus. Plant some corn 

 or barley in each. Give equal light and care and observe the 

 growth from time to time. 



Observation. Which shows the most vigorous growth after 

 two weeks' time ? 



Conclusions. 1. W T hat is the relation of humus (organic 

 matter) to the growth of plants ? 



2. What is one of the necessary conditions for a fertile soil ? 



e. Necessity for Mineral Matter 



Method. Partly fill four quart fruit jars, one with distilled 

 water, the second with nutrient solution 1 without calcium phos- 

 phate, the third with nutrient solution without ferric chloride, 

 and the fourth with nutrient solution. Place bean or corn 



1 A nutrient solution known as Sach's Solution may be made as follows : 



Potassium Nitrate 1.00 gram 



Sodium Chloride 0.50 gram 



Calcium Sulphate 0.50 gram 



Magnesium Sulphate 0.50 gram 



Calcium Phosphate . . . ...... . 0.50 gram 



Ferric Chloride . . . . ". . . . . . . 0.005 gram 



Distilled Water . ',, .... . . . . . 1000.00 grams 



Add the ferric chloride at the time the solution is to be used, by adding a 

 drop or so to the solution in the bottle used for the seedlings. 

 SHARPE'S LAB. MAN. 6 



