PLANT FOOD 141 



PRACTICAL QUESTIONS 



1. Will a pound of pop corn weigh the same after it has been 

 "popped"? (196.) 



2. Could any plant grow in a soil from which nitrogen was entirely 

 lacking? Phosphorus? Potash? Lime? (197.) 



3. Could it live in an atmosphere devoid of oxygen? Nitrogen? 

 Carbon dioxide? (197.) 



4. Is the same kind of fertilizer equally good for all kinds of soil? 

 For all kinds of plants? (198.) 



5. Is starch soluble in water? 



6. How does it get from the leaves where it is manufactured to the 

 rootstocks where it is stored? (200.) 



7. Why does too much watering interfere with the nourishment of 

 plants? 



8. Are ashes fit for fertilizers after being leached for lye? (197, 198.) 



9. Why will any but very small shrubs be dwarfed, or make very 

 slow growth in pots? (197, 198.) 



FIELD WORK 



Examine the underground parts of hardy winter herbs in your neigh- 

 borhood, and of any weeds or grasses that are particularly trouble- 

 some, and see if there is anything about the structure of these parts to 

 account for their persistence. Note the difference in the roots of the 

 same species in low, moist places and in dry ones ; between those of the 

 same kind of plants in different soils ; in sheltered and in exposed situ- 

 ations. Study the direction and position of the roots of trees and 

 shrubs with reference to any stream or body of water in the neighbor- 

 hood. (The elm, fig, mulberry, and willow are good subjects for such 

 observations.) Notice also whether there is any relation between the 

 underground parts and the leaf systems of plants in reference to drain- 

 age and transpiration. 



Observe the effect of root pull upon low herbs. Look along washes 

 and gullies for roots doing the office of stems, and note any changes o't 

 structure consequent thereon. Study the relative length and strength 

 of the root systems of different plants, with reference to their value as 

 soil binders, or their hurtfulness in damaging the walls of cellars, wells, 

 sewers, etc. Dig your trowel a few inches into the soil of any grove or 

 copse you happen to visit, and note the inextricable tangle of roots, and 

 consider the fierce competition for living room in the vegetable world 

 that it implies. 



Tests might be made of the different soils in the neighborhood of 

 the schoolhouse by planting seeds of different kinds and noting the 

 rate of germination ; first, without fertilizers, then by adding the differ- 

 ent elements in succession to see which is lacking. The field for study 

 suggested by this subject is almost inexhaustible. 



