114 A FIELD GUIDE IN NATURE-STUDY 



the other ja"r, pouring off the limewater to see if it is milky after shaking 

 it about. What process in your own body is the equivalent of this ? 



19. This same process of is going on in roots. 



Put a piece of blue litmus paper in a small bottle of water (or fill one partly 

 full of phenol-phthaleine solution to which has been added a drop of dilute 

 ammonia). Root out a small nasturtium or other small plant and set it 

 in the bottle, holding it in place with absorbent cotton packed into the 

 neck around the stem. Let stand for several days, noting changes in color 

 of the paper or solution. Meanwhile dip blue and red litmus paper into 

 dilute acid and dilute alkali, like ammonia, to note effect and to see that 

 litmus is a test for an acid. Try a drop of dilute alkali and of dilute acid 

 in the phenol-phthaleine solution. 



Why will plants not thrive as well in crocks or cans as in earthenware 

 pots ? How would you build a window box to avoid this difficulty ? 



20. If you girdle a tree what happens ? This shows what ? Peel off 

 the bark from a narrow ring at about the middle of a willow or basswood 

 twig. Set this in a bottle of water so the peeled ring is an inch or so above 

 the water. Plug the neck of the bottle with absorbent cotton. Does the 

 twig keep fresh? Evidently the water is going up to the leaves through 



Let stand for several weeks and see on which 



side of the ring the new roots grow. This shows what ? 



21. Soils. The chemical compounds that make up the tissues of plants 

 are chiefly carbon (C), hydrogen (H), oxygen (O), and nitrogen (N), together 

 with relatively small quantities of phosphorus (P), calcium (Ca), sulphur 

 (S), iron (Fe), etc. Which of these have we seen go into the plant from 

 the air ? Which from the soil ? Which of these several things is of most 

 importance may be judged from this experiment: Take seven pots of 

 clean sand. Mix thoroughly into No. i half as much pulverized sodium 

 nitrate as can be put on a dime; in No. 2 the same amount of sodium 

 phosphate; No. 3, sodium sulphate; No. 4, calcium sulphate; No. 5, iron 

 sulphate; No. 6, mix all these substances in equal amounts and add the 

 same quantity of the mixture; to No. 7 nothing is added. Plant twenty 

 oat or barley kernels in each pot, water carefully with distilled water or 

 rain water, and keep them growing for several weeks. Note the color and 

 general vigor of the plants. Record results and conclusions. 



22. Take 500 grams of garden soil and put it in an iron dish that you 

 have previously weighed. Set the pan with the soil on a ring stand over 

 a Bunsen burner that is burning with a flame that will keep the soil warm 

 but not burn it, or the pan may be warmed on the stove. At the end of 

 twenty-four hours let it cool and then weigh it and record the weight. The 

 loss of weight represents what ? Put the pan of soil back on the ring stand 



