PHYSIOLOGICAL PROCESSES IN PLANTS 77 



layer within the vial, and then removing it and fastening it 

 to the glass tube as for the egg membrane. Or fasten it to a 

 rubber stopper into which a glass tube has been inserted. 



Observation. Are there any changes in level in the two 

 liquids ? Which one, if any ? 



Conclusions. 1. Has the water in the jar penetrated the 

 membrane ? How do you know ? 



2. Has any glucose passed through the egg membrane into 

 the water ? (Test the water in the tumbler with Fehling's 

 solution for an answer.) 



3. If time permits, try making the liquid in the tumbler 

 denser than that in the membrane, and see whether the ex- 

 change is now more rapid in the opposite direction. Is the 

 greater flow towards or away from the thicker (denser) fluid ? 



4. How do roots get water and soluble salts from the 

 soil? 



5. Show how such substances would likely be forced up in 

 the stem. 



6. Why should the soil where seedlings are growing be 

 mellow, or loose and porous ? 



7. Expose a pot of wet soil to the direct action of the sun 

 for a few days. Do likewise with another pot of soil but cover 

 it with loose grass or straw to form a mulch. Which pot has 

 the most porous soil at the end of the period ? Which sort of 

 soil will remain the more porous that naturally covered with 

 grass, leaves, etc., or mulched, or that exposed to the direct rays 

 of the sun ? Show how one sort of soil needs breaking up or 

 tilling more than the other. 



8. Why is it that plants need fine loose soil for their root 

 hairs ? 



9. Why do plants wilt when first transplanted, and later 

 recover ? 



10. Show how liquid foods might get from food tubes into 

 near-by blood tubes. 



11. Show how oxygen of the air might get from the lungs 

 into near-by blood tubes. 



